diff --git a/.github/workflows/php.yml b/.github/workflows/php.yml
index 705d16c8..52bb0a33 100644
--- a/.github/workflows/php.yml
+++ b/.github/workflows/php.yml
@@ -4,6 +4,7 @@ on:
   push:
     branches:
       - main
+      - php74
   pull_request:
 
 jobs:
@@ -43,7 +44,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        php-versions: ['7.3', '7.4', '8.0', '8.1', '8.2', '8.3']
+        php-versions: ['7.4', '8.0', '8.1', '8.2', '8.3']
     steps:
       - uses: actions/checkout@v3
 
diff --git a/rector.php b/rector.php
new file mode 100644
index 00000000..76f9e5eb
--- /dev/null
+++ b/rector.php
@@ -0,0 +1,17 @@
+<?php
+
+declare(strict_types=1);
+
+use Rector\Config\RectorConfig;
+use Rector\TypeDeclaration\Rector\ClassMethod\AddVoidReturnTypeWhereNoReturnRector;
+
+return RectorConfig::configure()
+    ->withPaths([
+        __DIR__ . '/src',
+        __DIR__ . '/tests',
+    ])
+
+    ->withPhpSets(php74: true)
+    ->withRules([
+        AddVoidReturnTypeWhereNoReturnRector::class,
+    ]);
diff --git a/src/Fonts/TrueTypeFontFile.php b/src/Fonts/TrueTypeFontFile.php
index 455cce01..1ffa760c 100644
--- a/src/Fonts/TrueTypeFontFile.php
+++ b/src/Fonts/TrueTypeFontFile.php
@@ -44,10 +44,7 @@ public function getFamily(): string
 
     public function getWeight(): float
     {
-        if (isset($this->weightClass)) {
-            return $this->weightClass;
-        }
-        return $this->subfamily === 'Bold' || $this->subfamily === 'Bold Italic' ? 700 : 400;
+        return $this->weightClass ?? ($this->subfamily === 'Bold' || $this->subfamily === 'Bold Italic' ? 700 : 400);
     }
 
     public function isItalic(): bool
diff --git a/src/Nodes/Embedded/SVGForeignObject.php b/src/Nodes/Embedded/SVGForeignObject.php
index 51417885..b7deeeaf 100644
--- a/src/Nodes/Embedded/SVGForeignObject.php
+++ b/src/Nodes/Embedded/SVGForeignObject.php
@@ -10,7 +10,7 @@
  */
 class SVGForeignObject extends SVGNodeContainer
 {
-    const TAG_NAME = 'foreignObject';
+    public const TAG_NAME = 'foreignObject';
 
     public function __construct()
     {
diff --git a/src/Nodes/Embedded/SVGImage.php b/src/Nodes/Embedded/SVGImage.php
index be18a88a..46c0a073 100644
--- a/src/Nodes/Embedded/SVGImage.php
+++ b/src/Nodes/Embedded/SVGImage.php
@@ -14,7 +14,7 @@
  */
 class SVGImage extends SVGNodeContainer
 {
-    const TAG_NAME = 'image';
+    public const TAG_NAME = 'image';
 
     /**
      * @param string|null $href   The image path, URL or URI.
diff --git a/src/Nodes/Filters/SVGFEBlend.php b/src/Nodes/Filters/SVGFEBlend.php
index 5332a984..478842e8 100644
--- a/src/Nodes/Filters/SVGFEBlend.php
+++ b/src/Nodes/Filters/SVGFEBlend.php
@@ -10,7 +10,7 @@
  */
 class SVGFEBlend extends SVGNodeContainer
 {
-    const TAG_NAME = 'feBlend';
+    public const TAG_NAME = 'feBlend';
 
     public function __construct()
     {
diff --git a/src/Nodes/Filters/SVGFEColorMatrix.php b/src/Nodes/Filters/SVGFEColorMatrix.php
index 1f0393a1..e1812185 100644
--- a/src/Nodes/Filters/SVGFEColorMatrix.php
+++ b/src/Nodes/Filters/SVGFEColorMatrix.php
@@ -10,7 +10,7 @@
  */
 class SVGFEColorMatrix extends SVGNodeContainer
 {
-    const TAG_NAME = 'feColorMatrix';
+    public const TAG_NAME = 'feColorMatrix';
 
     public function __construct()
     {
diff --git a/src/Nodes/Filters/SVGFEComponentTransfer.php b/src/Nodes/Filters/SVGFEComponentTransfer.php
index 7f51596d..ec7a4b74 100644
--- a/src/Nodes/Filters/SVGFEComponentTransfer.php
+++ b/src/Nodes/Filters/SVGFEComponentTransfer.php
@@ -10,7 +10,7 @@
  */
 class SVGFEComponentTransfer extends SVGNodeContainer
 {
-    const TAG_NAME = 'feComponentTransfer';
+    public const TAG_NAME = 'feComponentTransfer';
 
     public function __construct()
     {
diff --git a/src/Nodes/Filters/SVGFEComposite.php b/src/Nodes/Filters/SVGFEComposite.php
index 21df7302..e4c69300 100644
--- a/src/Nodes/Filters/SVGFEComposite.php
+++ b/src/Nodes/Filters/SVGFEComposite.php
@@ -10,7 +10,7 @@
  */
 class SVGFEComposite extends SVGNodeContainer
 {
-    const TAG_NAME = 'feComposite';
+    public const TAG_NAME = 'feComposite';
 
     public function __construct()
     {
diff --git a/src/Nodes/Filters/SVGFEConvolveMatrix.php b/src/Nodes/Filters/SVGFEConvolveMatrix.php
index a9dcde62..43c050cf 100644
--- a/src/Nodes/Filters/SVGFEConvolveMatrix.php
+++ b/src/Nodes/Filters/SVGFEConvolveMatrix.php
@@ -10,7 +10,7 @@
  */
 class SVGFEConvolveMatrix extends SVGNodeContainer
 {
-    const TAG_NAME = 'feConvolveMatrix';
+    public const TAG_NAME = 'feConvolveMatrix';
 
     public function __construct()
     {
diff --git a/src/Nodes/Filters/SVGFEDiffuseLighting.php b/src/Nodes/Filters/SVGFEDiffuseLighting.php
index 9ba0052a..338c49de 100644
--- a/src/Nodes/Filters/SVGFEDiffuseLighting.php
+++ b/src/Nodes/Filters/SVGFEDiffuseLighting.php
@@ -10,7 +10,7 @@
  */
 class SVGFEDiffuseLighting extends SVGNodeContainer
 {
-    const TAG_NAME = 'feDiffuseLighting';
+    public const TAG_NAME = 'feDiffuseLighting';
 
     public function __construct()
     {
diff --git a/src/Nodes/Filters/SVGFEDisplacementMap.php b/src/Nodes/Filters/SVGFEDisplacementMap.php
index cc198b2d..33604b3d 100644
--- a/src/Nodes/Filters/SVGFEDisplacementMap.php
+++ b/src/Nodes/Filters/SVGFEDisplacementMap.php
@@ -10,7 +10,7 @@
  */
 class SVGFEDisplacementMap extends SVGNodeContainer
 {
-    const TAG_NAME = 'feDisplacementMap';
+    public const TAG_NAME = 'feDisplacementMap';
 
     public function __construct()
     {
diff --git a/src/Nodes/Filters/SVGFEDistantLight.php b/src/Nodes/Filters/SVGFEDistantLight.php
index 24673db3..f4884fd9 100644
--- a/src/Nodes/Filters/SVGFEDistantLight.php
+++ b/src/Nodes/Filters/SVGFEDistantLight.php
@@ -10,7 +10,7 @@
  */
 class SVGFEDistantLight extends SVGNodeContainer
 {
-    const TAG_NAME = 'feDistantLight';
+    public const TAG_NAME = 'feDistantLight';
 
     public function __construct()
     {
diff --git a/src/Nodes/Filters/SVGFEDropShadow.php b/src/Nodes/Filters/SVGFEDropShadow.php
index d9827cda..ceeb98d9 100644
--- a/src/Nodes/Filters/SVGFEDropShadow.php
+++ b/src/Nodes/Filters/SVGFEDropShadow.php
@@ -10,7 +10,7 @@
  */
 class SVGFEDropShadow extends SVGNodeContainer
 {
-    const TAG_NAME = 'feDropShadow';
+    public const TAG_NAME = 'feDropShadow';
 
     public function __construct()
     {
diff --git a/src/Nodes/Filters/SVGFEFlood.php b/src/Nodes/Filters/SVGFEFlood.php
index 43d5b8c4..5a00596e 100644
--- a/src/Nodes/Filters/SVGFEFlood.php
+++ b/src/Nodes/Filters/SVGFEFlood.php
@@ -10,7 +10,7 @@
  */
 class SVGFEFlood extends SVGNodeContainer
 {
-    const TAG_NAME = 'feFlood';
+    public const TAG_NAME = 'feFlood';
 
     public function __construct()
     {
diff --git a/src/Nodes/Filters/SVGFEFuncA.php b/src/Nodes/Filters/SVGFEFuncA.php
index 75b8b47e..1a022770 100644
--- a/src/Nodes/Filters/SVGFEFuncA.php
+++ b/src/Nodes/Filters/SVGFEFuncA.php
@@ -10,7 +10,7 @@
  */
 class SVGFEFuncA extends SVGNodeContainer
 {
-    const TAG_NAME = 'feFuncA';
+    public const TAG_NAME = 'feFuncA';
 
     public function __construct()
     {
diff --git a/src/Nodes/Filters/SVGFEFuncB.php b/src/Nodes/Filters/SVGFEFuncB.php
index 468bd44b..82f433c7 100644
--- a/src/Nodes/Filters/SVGFEFuncB.php
+++ b/src/Nodes/Filters/SVGFEFuncB.php
@@ -10,7 +10,7 @@
  */
 class SVGFEFuncB extends SVGNodeContainer
 {
-    const TAG_NAME = 'feFuncB';
+    public const TAG_NAME = 'feFuncB';
 
     public function __construct()
     {
diff --git a/src/Nodes/Filters/SVGFEFuncG.php b/src/Nodes/Filters/SVGFEFuncG.php
index 646bd5b6..1a1c27f2 100644
--- a/src/Nodes/Filters/SVGFEFuncG.php
+++ b/src/Nodes/Filters/SVGFEFuncG.php
@@ -10,7 +10,7 @@
  */
 class SVGFEFuncG extends SVGNodeContainer
 {
-    const TAG_NAME = 'feFuncG';
+    public const TAG_NAME = 'feFuncG';
 
     public function __construct()
     {
diff --git a/src/Nodes/Filters/SVGFEFuncR.php b/src/Nodes/Filters/SVGFEFuncR.php
index dd4056f7..224bb58f 100644
--- a/src/Nodes/Filters/SVGFEFuncR.php
+++ b/src/Nodes/Filters/SVGFEFuncR.php
@@ -10,7 +10,7 @@
  */
 class SVGFEFuncR extends SVGNodeContainer
 {
-    const TAG_NAME = 'feFuncR';
+    public const TAG_NAME = 'feFuncR';
 
     public function __construct()
     {
diff --git a/src/Nodes/Filters/SVGFEGaussianBlur.php b/src/Nodes/Filters/SVGFEGaussianBlur.php
index 740a8bb3..89a5097c 100644
--- a/src/Nodes/Filters/SVGFEGaussianBlur.php
+++ b/src/Nodes/Filters/SVGFEGaussianBlur.php
@@ -10,7 +10,7 @@
  */
 class SVGFEGaussianBlur extends SVGNodeContainer
 {
-    const TAG_NAME = 'feGaussianBlur';
+    public const TAG_NAME = 'feGaussianBlur';
 
     public function __construct()
     {
diff --git a/src/Nodes/Filters/SVGFEImage.php b/src/Nodes/Filters/SVGFEImage.php
index 2a31d904..eb0ffdb1 100644
--- a/src/Nodes/Filters/SVGFEImage.php
+++ b/src/Nodes/Filters/SVGFEImage.php
@@ -10,7 +10,7 @@
  */
 class SVGFEImage extends SVGNodeContainer
 {
-    const TAG_NAME = 'feImage';
+    public const TAG_NAME = 'feImage';
 
     public function __construct()
     {
diff --git a/src/Nodes/Filters/SVGFEMerge.php b/src/Nodes/Filters/SVGFEMerge.php
index 70fc367e..366b6acf 100644
--- a/src/Nodes/Filters/SVGFEMerge.php
+++ b/src/Nodes/Filters/SVGFEMerge.php
@@ -10,7 +10,7 @@
  */
 class SVGFEMerge extends SVGNodeContainer
 {
-    const TAG_NAME = 'feMerge';
+    public const TAG_NAME = 'feMerge';
 
     public function __construct()
     {
diff --git a/src/Nodes/Filters/SVGFEMergeNode.php b/src/Nodes/Filters/SVGFEMergeNode.php
index 73c0167c..a480f639 100644
--- a/src/Nodes/Filters/SVGFEMergeNode.php
+++ b/src/Nodes/Filters/SVGFEMergeNode.php
@@ -10,7 +10,7 @@
  */
 class SVGFEMergeNode extends SVGNodeContainer
 {
-    const TAG_NAME = 'feMergeNode';
+    public const TAG_NAME = 'feMergeNode';
 
     public function __construct()
     {
diff --git a/src/Nodes/Filters/SVGFEMorphology.php b/src/Nodes/Filters/SVGFEMorphology.php
index 3c99918c..fe803d1f 100644
--- a/src/Nodes/Filters/SVGFEMorphology.php
+++ b/src/Nodes/Filters/SVGFEMorphology.php
@@ -10,7 +10,7 @@
  */
 class SVGFEMorphology extends SVGNodeContainer
 {
-    const TAG_NAME = 'feMorphology';
+    public const TAG_NAME = 'feMorphology';
 
     public function __construct()
     {
diff --git a/src/Nodes/Filters/SVGFEOffset.php b/src/Nodes/Filters/SVGFEOffset.php
index ef18c507..8529a647 100644
--- a/src/Nodes/Filters/SVGFEOffset.php
+++ b/src/Nodes/Filters/SVGFEOffset.php
@@ -10,7 +10,7 @@
  */
 class SVGFEOffset extends SVGNodeContainer
 {
-    const TAG_NAME = 'feOffset';
+    public const TAG_NAME = 'feOffset';
 
     public function __construct()
     {
diff --git a/src/Nodes/Filters/SVGFEPointLight.php b/src/Nodes/Filters/SVGFEPointLight.php
index 933f9d8a..6910c47b 100644
--- a/src/Nodes/Filters/SVGFEPointLight.php
+++ b/src/Nodes/Filters/SVGFEPointLight.php
@@ -10,7 +10,7 @@
  */
 class SVGFEPointLight extends SVGNodeContainer
 {
-    const TAG_NAME = 'fePointLight';
+    public const TAG_NAME = 'fePointLight';
 
     public function __construct()
     {
diff --git a/src/Nodes/Filters/SVGFESpecularLighting.php b/src/Nodes/Filters/SVGFESpecularLighting.php
index 5af754bd..1e2aee5f 100644
--- a/src/Nodes/Filters/SVGFESpecularLighting.php
+++ b/src/Nodes/Filters/SVGFESpecularLighting.php
@@ -10,7 +10,7 @@
  */
 class SVGFESpecularLighting extends SVGNodeContainer
 {
-    const TAG_NAME = 'feSpecularLighting';
+    public const TAG_NAME = 'feSpecularLighting';
 
     public function __construct()
     {
diff --git a/src/Nodes/Filters/SVGFESpotLight.php b/src/Nodes/Filters/SVGFESpotLight.php
index 682dd5e5..2bde7e10 100644
--- a/src/Nodes/Filters/SVGFESpotLight.php
+++ b/src/Nodes/Filters/SVGFESpotLight.php
@@ -10,7 +10,7 @@
  */
 class SVGFESpotLight extends SVGNodeContainer
 {
-    const TAG_NAME = 'feSpotLight';
+    public const TAG_NAME = 'feSpotLight';
 
     public function __construct()
     {
diff --git a/src/Nodes/Filters/SVGFETile.php b/src/Nodes/Filters/SVGFETile.php
index d326fb3d..7fbb39cb 100644
--- a/src/Nodes/Filters/SVGFETile.php
+++ b/src/Nodes/Filters/SVGFETile.php
@@ -10,7 +10,7 @@
  */
 class SVGFETile extends SVGNodeContainer
 {
-    const TAG_NAME = 'feTile';
+    public const TAG_NAME = 'feTile';
 
     public function __construct()
     {
diff --git a/src/Nodes/Filters/SVGFETurbulence.php b/src/Nodes/Filters/SVGFETurbulence.php
index 5934da31..85890074 100644
--- a/src/Nodes/Filters/SVGFETurbulence.php
+++ b/src/Nodes/Filters/SVGFETurbulence.php
@@ -10,7 +10,7 @@
  */
 class SVGFETurbulence extends SVGNodeContainer
 {
-    const TAG_NAME = 'feTurbulence';
+    public const TAG_NAME = 'feTurbulence';
 
     public function __construct()
     {
diff --git a/src/Nodes/Filters/SVGFilter.php b/src/Nodes/Filters/SVGFilter.php
index 25b457f6..1465be96 100644
--- a/src/Nodes/Filters/SVGFilter.php
+++ b/src/Nodes/Filters/SVGFilter.php
@@ -10,7 +10,7 @@
  */
 class SVGFilter extends SVGNodeContainer
 {
-    const TAG_NAME = 'filter';
+    public const TAG_NAME = 'filter';
 
     public function __construct()
     {
diff --git a/src/Nodes/Presentation/SVGAnimate.php b/src/Nodes/Presentation/SVGAnimate.php
index 3470a091..eddbd03f 100644
--- a/src/Nodes/Presentation/SVGAnimate.php
+++ b/src/Nodes/Presentation/SVGAnimate.php
@@ -10,7 +10,7 @@
  */
 class SVGAnimate extends SVGNodeContainer
 {
-    const TAG_NAME = 'animate';
+    public const TAG_NAME = 'animate';
 
     public function __construct()
     {
diff --git a/src/Nodes/Presentation/SVGAnimateMotion.php b/src/Nodes/Presentation/SVGAnimateMotion.php
index 3d7a5d72..ef01f83f 100644
--- a/src/Nodes/Presentation/SVGAnimateMotion.php
+++ b/src/Nodes/Presentation/SVGAnimateMotion.php
@@ -10,7 +10,7 @@
  */
 class SVGAnimateMotion extends SVGNodeContainer
 {
-    const TAG_NAME = 'animateMotion';
+    public const TAG_NAME = 'animateMotion';
 
     public function __construct()
     {
diff --git a/src/Nodes/Presentation/SVGAnimateTransform.php b/src/Nodes/Presentation/SVGAnimateTransform.php
index ff68c95c..aa01c1ba 100644
--- a/src/Nodes/Presentation/SVGAnimateTransform.php
+++ b/src/Nodes/Presentation/SVGAnimateTransform.php
@@ -10,7 +10,7 @@
  */
 class SVGAnimateTransform extends SVGNodeContainer
 {
-    const TAG_NAME = 'animateTransform';
+    public const TAG_NAME = 'animateTransform';
 
     public function __construct()
     {
diff --git a/src/Nodes/Presentation/SVGLinearGradient.php b/src/Nodes/Presentation/SVGLinearGradient.php
index 2c1ea7e7..ff88acfd 100644
--- a/src/Nodes/Presentation/SVGLinearGradient.php
+++ b/src/Nodes/Presentation/SVGLinearGradient.php
@@ -10,7 +10,7 @@
  */
 class SVGLinearGradient extends SVGNodeContainer
 {
-    const TAG_NAME = 'linearGradient';
+    public const TAG_NAME = 'linearGradient';
 
     public function __construct()
     {
diff --git a/src/Nodes/Presentation/SVGMPath.php b/src/Nodes/Presentation/SVGMPath.php
index accb0939..6ba3964e 100644
--- a/src/Nodes/Presentation/SVGMPath.php
+++ b/src/Nodes/Presentation/SVGMPath.php
@@ -10,7 +10,7 @@
  */
 class SVGMPath extends SVGNodeContainer
 {
-    const TAG_NAME = 'mpath';
+    public const TAG_NAME = 'mpath';
 
     public function __construct()
     {
diff --git a/src/Nodes/Presentation/SVGRadialGradient.php b/src/Nodes/Presentation/SVGRadialGradient.php
index f275ef56..d9f41f93 100644
--- a/src/Nodes/Presentation/SVGRadialGradient.php
+++ b/src/Nodes/Presentation/SVGRadialGradient.php
@@ -10,7 +10,7 @@
  */
 class SVGRadialGradient extends SVGNodeContainer
 {
-    const TAG_NAME = 'radialGradient';
+    public const TAG_NAME = 'radialGradient';
 
     public function __construct()
     {
diff --git a/src/Nodes/Presentation/SVGSet.php b/src/Nodes/Presentation/SVGSet.php
index 2d56b370..f8713cc6 100644
--- a/src/Nodes/Presentation/SVGSet.php
+++ b/src/Nodes/Presentation/SVGSet.php
@@ -10,7 +10,7 @@
  */
 class SVGSet extends SVGNodeContainer
 {
-    const TAG_NAME = 'set';
+    public const TAG_NAME = 'set';
 
     public function __construct()
     {
diff --git a/src/Nodes/Presentation/SVGStop.php b/src/Nodes/Presentation/SVGStop.php
index a86f4b27..3d2180b1 100644
--- a/src/Nodes/Presentation/SVGStop.php
+++ b/src/Nodes/Presentation/SVGStop.php
@@ -10,7 +10,7 @@
  */
 class SVGStop extends SVGNodeContainer
 {
-    const TAG_NAME = 'stop';
+    public const TAG_NAME = 'stop';
 
     public function __construct()
     {
diff --git a/src/Nodes/Presentation/SVGView.php b/src/Nodes/Presentation/SVGView.php
index f72cfae8..1f2c96b0 100644
--- a/src/Nodes/Presentation/SVGView.php
+++ b/src/Nodes/Presentation/SVGView.php
@@ -10,7 +10,7 @@
  */
 class SVGView extends SVGNodeContainer
 {
-    const TAG_NAME = 'view';
+    public const TAG_NAME = 'view';
 
     public function __construct()
     {
diff --git a/src/Nodes/SVGNodeContainer.php b/src/Nodes/SVGNodeContainer.php
index af81c15c..aecb7695 100644
--- a/src/Nodes/SVGNodeContainer.php
+++ b/src/Nodes/SVGNodeContainer.php
@@ -49,7 +49,7 @@ public function addChild(SVGNode $node, int $index = null): SVGNodeContainer
             $node->parent->removeChild($node);
         }
 
-        $index = ($index !== null) ? $index : count($this->children);
+        $index = $index ?? count($this->children);
 
         // insert and set new parent
         array_splice($this->children, $index, 0, [$node]);
diff --git a/src/Nodes/Shapes/SVGCircle.php b/src/Nodes/Shapes/SVGCircle.php
index ffa2599d..f519abea 100644
--- a/src/Nodes/Shapes/SVGCircle.php
+++ b/src/Nodes/Shapes/SVGCircle.php
@@ -13,7 +13,7 @@
  */
 class SVGCircle extends SVGNodeContainer
 {
-    const TAG_NAME = 'circle';
+    public const TAG_NAME = 'circle';
 
     /**
      * @param mixed $cx The center's x coordinate.
diff --git a/src/Nodes/Shapes/SVGEllipse.php b/src/Nodes/Shapes/SVGEllipse.php
index 015f5a6c..a1278b77 100644
--- a/src/Nodes/Shapes/SVGEllipse.php
+++ b/src/Nodes/Shapes/SVGEllipse.php
@@ -13,7 +13,7 @@
  */
 class SVGEllipse extends SVGNodeContainer
 {
-    const TAG_NAME = 'ellipse';
+    public const TAG_NAME = 'ellipse';
 
     /**
      * @param mixed $cx The center's x coordinate.
diff --git a/src/Nodes/Shapes/SVGLine.php b/src/Nodes/Shapes/SVGLine.php
index 5de5fe6b..5009be59 100644
--- a/src/Nodes/Shapes/SVGLine.php
+++ b/src/Nodes/Shapes/SVGLine.php
@@ -13,7 +13,7 @@
  */
 class SVGLine extends SVGNodeContainer
 {
-    const TAG_NAME = 'line';
+    public const TAG_NAME = 'line';
 
     /**
      * @param mixed $x1 The first point's x coordinate.
diff --git a/src/Nodes/Shapes/SVGPath.php b/src/Nodes/Shapes/SVGPath.php
index ae8b2ef9..ba1cc955 100644
--- a/src/Nodes/Shapes/SVGPath.php
+++ b/src/Nodes/Shapes/SVGPath.php
@@ -12,7 +12,7 @@
  */
 class SVGPath extends SVGNodeContainer
 {
-    const TAG_NAME = 'path';
+    public const TAG_NAME = 'path';
 
     private static $pathParser;
 
diff --git a/src/Nodes/Shapes/SVGPolygon.php b/src/Nodes/Shapes/SVGPolygon.php
index 3c0da35a..bb5aab7f 100644
--- a/src/Nodes/Shapes/SVGPolygon.php
+++ b/src/Nodes/Shapes/SVGPolygon.php
@@ -11,7 +11,7 @@
  */
 class SVGPolygon extends SVGPolygonalShape
 {
-    const TAG_NAME = 'polygon';
+    public const TAG_NAME = 'polygon';
 
     /**
      * @param array[] $points Array of points (float 2-tuples).
diff --git a/src/Nodes/Shapes/SVGPolygonalShape.php b/src/Nodes/Shapes/SVGPolygonalShape.php
index 01e86315..ec580e4a 100644
--- a/src/Nodes/Shapes/SVGPolygonalShape.php
+++ b/src/Nodes/Shapes/SVGPolygonalShape.php
@@ -35,7 +35,7 @@ public function __construct(array $points = null)
     public function addPoint($a, $b = null): SVGPolygonalShape
     {
         if (is_array($a)) {
-            list($a, $b) = $a;
+            [$a, $b] = $a;
         }
 
         $pointsAttribute = $this->getAttribute('points') ?: '';
diff --git a/src/Nodes/Shapes/SVGPolyline.php b/src/Nodes/Shapes/SVGPolyline.php
index c2c74f66..7575f098 100644
--- a/src/Nodes/Shapes/SVGPolyline.php
+++ b/src/Nodes/Shapes/SVGPolyline.php
@@ -11,7 +11,7 @@
  */
 class SVGPolyline extends SVGPolygonalShape
 {
-    const TAG_NAME = 'polyline';
+    public const TAG_NAME = 'polyline';
 
     /**
      * @param array[] $points Array of points (float 2-tuples).
diff --git a/src/Nodes/Shapes/SVGRect.php b/src/Nodes/Shapes/SVGRect.php
index f3629790..20f3346e 100644
--- a/src/Nodes/Shapes/SVGRect.php
+++ b/src/Nodes/Shapes/SVGRect.php
@@ -13,7 +13,7 @@
  */
 class SVGRect extends SVGNodeContainer
 {
-    const TAG_NAME = 'rect';
+    public const TAG_NAME = 'rect';
 
     /**
      * @param mixed $x      The x coordinate of the upper left corner.
diff --git a/src/Nodes/Structures/SVGClipPath.php b/src/Nodes/Structures/SVGClipPath.php
index 5752738d..4eab6469 100644
--- a/src/Nodes/Structures/SVGClipPath.php
+++ b/src/Nodes/Structures/SVGClipPath.php
@@ -10,7 +10,7 @@
  */
 class SVGClipPath extends SVGNodeContainer
 {
-    const TAG_NAME = 'clipPath';
+    public const TAG_NAME = 'clipPath';
 
     public function __construct(string $id = null)
     {
diff --git a/src/Nodes/Structures/SVGDefs.php b/src/Nodes/Structures/SVGDefs.php
index 64ed2fab..57364550 100644
--- a/src/Nodes/Structures/SVGDefs.php
+++ b/src/Nodes/Structures/SVGDefs.php
@@ -10,7 +10,7 @@
  */
 class SVGDefs extends SVGNodeContainer
 {
-    const TAG_NAME = 'defs';
+    public const TAG_NAME = 'defs';
 
     public function __construct()
     {
diff --git a/src/Nodes/Structures/SVGDocumentFragment.php b/src/Nodes/Structures/SVGDocumentFragment.php
index ac14fedd..b8404e03 100644
--- a/src/Nodes/Structures/SVGDocumentFragment.php
+++ b/src/Nodes/Structures/SVGDocumentFragment.php
@@ -13,7 +13,7 @@
  */
 class SVGDocumentFragment extends SVGNodeContainer
 {
-    const TAG_NAME = 'svg';
+    public const TAG_NAME = 'svg';
 
     /** @var array $initialStyles A map of style keys to their defaults. */
     private static $initialStyles = [
diff --git a/src/Nodes/Structures/SVGGroup.php b/src/Nodes/Structures/SVGGroup.php
index ce392cc9..34fbe5c0 100644
--- a/src/Nodes/Structures/SVGGroup.php
+++ b/src/Nodes/Structures/SVGGroup.php
@@ -9,7 +9,7 @@
  */
 class SVGGroup extends SVGNodeContainer
 {
-    const TAG_NAME = 'g';
+    public const TAG_NAME = 'g';
 
     public function __construct()
     {
diff --git a/src/Nodes/Structures/SVGLinkGroup.php b/src/Nodes/Structures/SVGLinkGroup.php
index 19bd4aaa..07d7f0a6 100644
--- a/src/Nodes/Structures/SVGLinkGroup.php
+++ b/src/Nodes/Structures/SVGLinkGroup.php
@@ -9,7 +9,7 @@
  */
 class SVGLinkGroup extends SVGNodeContainer
 {
-    const TAG_NAME = 'a';
+    public const TAG_NAME = 'a';
 
     public function __construct()
     {
diff --git a/src/Nodes/Structures/SVGMarker.php b/src/Nodes/Structures/SVGMarker.php
index 55336c83..3ee895d0 100644
--- a/src/Nodes/Structures/SVGMarker.php
+++ b/src/Nodes/Structures/SVGMarker.php
@@ -10,7 +10,7 @@
  */
 class SVGMarker extends SVGNodeContainer
 {
-    const TAG_NAME = 'marker';
+    public const TAG_NAME = 'marker';
 
     public function __construct()
     {
diff --git a/src/Nodes/Structures/SVGMask.php b/src/Nodes/Structures/SVGMask.php
index 11d49776..5b9ff174 100644
--- a/src/Nodes/Structures/SVGMask.php
+++ b/src/Nodes/Structures/SVGMask.php
@@ -10,7 +10,7 @@
  */
 class SVGMask extends SVGNodeContainer
 {
-    const TAG_NAME = 'mask';
+    public const TAG_NAME = 'mask';
 
     public function __construct()
     {
diff --git a/src/Nodes/Structures/SVGMetadata.php b/src/Nodes/Structures/SVGMetadata.php
index c75c6aaf..91e556b6 100644
--- a/src/Nodes/Structures/SVGMetadata.php
+++ b/src/Nodes/Structures/SVGMetadata.php
@@ -10,7 +10,7 @@
  */
 class SVGMetadata extends SVGNodeContainer
 {
-    const TAG_NAME = 'metadata';
+    public const TAG_NAME = 'metadata';
 
     public function __construct()
     {
diff --git a/src/Nodes/Structures/SVGPattern.php b/src/Nodes/Structures/SVGPattern.php
index 914bda27..17cedc75 100644
--- a/src/Nodes/Structures/SVGPattern.php
+++ b/src/Nodes/Structures/SVGPattern.php
@@ -10,7 +10,7 @@
  */
 class SVGPattern extends SVGNodeContainer
 {
-    const TAG_NAME = 'pattern';
+    public const TAG_NAME = 'pattern';
 
     public function __construct()
     {
diff --git a/src/Nodes/Structures/SVGScript.php b/src/Nodes/Structures/SVGScript.php
index 4f915498..c3378d63 100644
--- a/src/Nodes/Structures/SVGScript.php
+++ b/src/Nodes/Structures/SVGScript.php
@@ -11,7 +11,7 @@
  */
 class SVGScript extends SVGNodeContainer implements CDataContainer
 {
-    const TAG_NAME = 'script';
+    public const TAG_NAME = 'script';
 
     /**
      * @param string $content The script content.
diff --git a/src/Nodes/Structures/SVGStyle.php b/src/Nodes/Structures/SVGStyle.php
index d97cc092..aac09c12 100644
--- a/src/Nodes/Structures/SVGStyle.php
+++ b/src/Nodes/Structures/SVGStyle.php
@@ -12,7 +12,7 @@
  */
 class SVGStyle extends SVGNodeContainer implements CDataContainer
 {
-    const TAG_NAME = 'style';
+    public const TAG_NAME = 'style';
 
     /**
      * @param string $css   The CSS data rules.
diff --git a/src/Nodes/Structures/SVGSwitch.php b/src/Nodes/Structures/SVGSwitch.php
index 5bca9514..706825ef 100644
--- a/src/Nodes/Structures/SVGSwitch.php
+++ b/src/Nodes/Structures/SVGSwitch.php
@@ -10,7 +10,7 @@
  */
 class SVGSwitch extends SVGNodeContainer
 {
-    const TAG_NAME = 'switch';
+    public const TAG_NAME = 'switch';
 
     public function __construct()
     {
diff --git a/src/Nodes/Structures/SVGSymbol.php b/src/Nodes/Structures/SVGSymbol.php
index 8fd82664..9bb92b37 100644
--- a/src/Nodes/Structures/SVGSymbol.php
+++ b/src/Nodes/Structures/SVGSymbol.php
@@ -10,7 +10,7 @@
  */
 class SVGSymbol extends SVGNodeContainer
 {
-    const TAG_NAME = 'symbol';
+    public const TAG_NAME = 'symbol';
 
     public function __construct()
     {
diff --git a/src/Nodes/Structures/SVGUse.php b/src/Nodes/Structures/SVGUse.php
index 30f51ab1..a78e3089 100644
--- a/src/Nodes/Structures/SVGUse.php
+++ b/src/Nodes/Structures/SVGUse.php
@@ -10,7 +10,7 @@
  */
 class SVGUse extends SVGNodeContainer
 {
-    const TAG_NAME = 'use';
+    public const TAG_NAME = 'use';
 
     public function __construct()
     {
diff --git a/src/Nodes/Texts/SVGDesc.php b/src/Nodes/Texts/SVGDesc.php
index 3416afcf..f2b0f9fc 100644
--- a/src/Nodes/Texts/SVGDesc.php
+++ b/src/Nodes/Texts/SVGDesc.php
@@ -10,7 +10,7 @@
  */
 class SVGDesc extends SVGNodeContainer
 {
-    const TAG_NAME = 'desc';
+    public const TAG_NAME = 'desc';
 
     public function __construct()
     {
diff --git a/src/Nodes/Texts/SVGTSpan.php b/src/Nodes/Texts/SVGTSpan.php
index ebfaa079..4231eb01 100644
--- a/src/Nodes/Texts/SVGTSpan.php
+++ b/src/Nodes/Texts/SVGTSpan.php
@@ -10,7 +10,7 @@
  */
 class SVGTSpan extends SVGNodeContainer
 {
-    const TAG_NAME = 'tspan';
+    public const TAG_NAME = 'tspan';
 
     public function __construct()
     {
diff --git a/src/Nodes/Texts/SVGText.php b/src/Nodes/Texts/SVGText.php
index 1b1200c3..476e0567 100644
--- a/src/Nodes/Texts/SVGText.php
+++ b/src/Nodes/Texts/SVGText.php
@@ -25,7 +25,7 @@
  */
 class SVGText extends SVGNodeContainer
 {
-    const TAG_NAME = 'text';
+    public const TAG_NAME = 'text';
 
     public function __construct(string $text = '', $x = 0, $y = 0)
     {
diff --git a/src/Nodes/Texts/SVGTextPath.php b/src/Nodes/Texts/SVGTextPath.php
index e4d521d3..6e5223b3 100644
--- a/src/Nodes/Texts/SVGTextPath.php
+++ b/src/Nodes/Texts/SVGTextPath.php
@@ -10,7 +10,7 @@
  */
 class SVGTextPath extends SVGNodeContainer
 {
-    const TAG_NAME = 'textPath';
+    public const TAG_NAME = 'textPath';
 
     public function __construct()
     {
diff --git a/src/Nodes/Texts/SVGTitle.php b/src/Nodes/Texts/SVGTitle.php
index acdf14e2..2cbe3c7e 100644
--- a/src/Nodes/Texts/SVGTitle.php
+++ b/src/Nodes/Texts/SVGTitle.php
@@ -10,7 +10,7 @@
  */
 class SVGTitle extends SVGNodeContainer
 {
-    const TAG_NAME = 'title';
+    public const TAG_NAME = 'title';
 
     public function __construct(string $text = '')
     {
diff --git a/src/Rasterization/Path/ArcApproximator.php b/src/Rasterization/Path/ArcApproximator.php
index d4541d67..9bae8a06 100644
--- a/src/Rasterization/Path/ArcApproximator.php
+++ b/src/Rasterization/Path/ArcApproximator.php
@@ -59,7 +59,7 @@ public function approximate(
         $cosr = cos($rotation);
         $sinr = sin($rotation);
 
-        list($center, $radiusX, $radiusY, $angleStart, $angleDelta) =
+        [$center, $radiusX, $radiusY, $angleStart, $angleDelta] =
             self::endpointToCenter($start, $end, $large, $sweep, $radiusX, $radiusY, $cosr, $sinr);
 
         $dist = abs($end[0] - $start[0]) + abs($end[1] - $start[1]);
diff --git a/src/Rasterization/Path/PathApproximator.php b/src/Rasterization/Path/PathApproximator.php
index 1fad8f94..6fa18e1f 100644
--- a/src/Rasterization/Path/PathApproximator.php
+++ b/src/Rasterization/Path/PathApproximator.php
@@ -222,7 +222,7 @@ private static function reflectPoint(array $p, array $r): array
      */
     private function moveTo(string $id, array $args): void
     {
-        list($x, $y) = $args;
+        [$x, $y] = $args;
         if ($id === 'm') {
             $x += $this->posX;
             $y += $this->posY;
@@ -245,7 +245,7 @@ private function moveTo(string $id, array $args): void
      */
     private function lineTo(string $id, array $args): void
     {
-        list($x, $y) = $args;
+        [$x, $y] = $args;
         if ($id === 'l') {
             $x += $this->posX;
             $y += $this->posY;
@@ -337,7 +337,7 @@ private function curveToCubic(string $id, array $args): void
         }
 
         $this->cubicOld = $p2;
-        list($this->posX, $this->posY) = $p3;
+        [$this->posX, $this->posY] = $p3;
 
         $this->transform->map($p1[0], $p1[1]);
         $this->transform->map($p2[0], $p2[1]);
@@ -379,7 +379,7 @@ private function curveToCubicSmooth(string $id, array $args): void
         }
 
         $this->cubicOld = $p2;
-        list($this->posX, $this->posY) = $p3;
+        [$this->posX, $this->posY] = $p3;
 
         $this->transform->map($p1[0], $p1[1]);
         $this->transform->map($p2[0], $p2[1]);
@@ -414,7 +414,7 @@ private function curveToQuadratic(string $id, array $args): void
         }
 
         $this->quadraticOld = $p1;
-        list($this->posX, $this->posY) = $p2;
+        [$this->posX, $this->posY] = $p2;
 
         $this->transform->map($p1[0], $p1[1]);
         $this->transform->map($p2[0], $p2[1]);
@@ -451,7 +451,7 @@ private function curveToQuadraticSmooth(string $id, array $args): void
         }
 
         $this->quadraticOld = $p1;
-        list($this->posX, $this->posY) = $p2;
+        [$this->posX, $this->posY] = $p2;
 
         $this->transform->map($p1[0], $p1[1]);
         $this->transform->map($p2[0], $p2[1]);
@@ -494,7 +494,7 @@ private function arcTo(string $id, array $args): void
             $p1[1] += $this->posY;
         }
 
-        list($this->posX, $this->posY) = $p1;
+        [$this->posX, $this->posY] = $p1;
 
         // guess a scale factor
         $scaledRx = $rx;
diff --git a/src/Rasterization/Renderers/PathRendererImplementation.php b/src/Rasterization/Renderers/PathRendererImplementation.php
index 397e1cbc..63f68f0f 100644
--- a/src/Rasterization/Renderers/PathRendererImplementation.php
+++ b/src/Rasterization/Renderers/PathRendererImplementation.php
@@ -59,7 +59,7 @@ public static function fillMultipath($image, array $subpaths, int $color, string
         imagesetthickness($image, 1);
 
         // Sort the edges by their maximum y value, descending (i.e., edges that extend further down are sorted first).
-        usort($edges, ['SVG\Rasterization\Renderers\PathRendererEdge', 'compareMaxY']);
+        usort($edges, [\SVG\Rasterization\Renderers\PathRendererEdge::class, 'compareMaxY']);
         // Now the maxY of the entire path is just the maxY of the edge sorted first.
         // Since there is no way to know which edge has the minY, we cannot do the same for that and have to compute
         // it during the loop instead.
@@ -92,7 +92,7 @@ public static function fillMultipath($image, array $subpaths, int $color, string
 
             if (!empty($activeEdges)) {
                 // Now sort the active edges from rightmost to leftmost (i.e., by x descending).
-                usort($activeEdges, ['SVG\Rasterization\Renderers\PathRendererEdge', 'compareX']);
+                usort($activeEdges, [\SVG\Rasterization\Renderers\PathRendererEdge::class, 'compareX']);
 
                 $windingNumber = $evenOdd ? 0 : $activeEdges[0]->direction;
 
diff --git a/src/Reading/AttributeRegistry.php b/src/Reading/AttributeRegistry.php
index 09030583..63483415 100644
--- a/src/Reading/AttributeRegistry.php
+++ b/src/Reading/AttributeRegistry.php
@@ -50,9 +50,9 @@ class AttributeRegistry
      * for SVG attribute to CSS property conversion.
      */
     private static $styleConverters = [
-        'font-size'         => 'SVG\Reading\LengthAttributeConverter',
-        'letter-spacing'    => 'SVG\Reading\LengthAttributeConverter',
-        'word-spacing'      => 'SVG\Reading\LengthAttributeConverter',
+        'font-size'         => \SVG\Reading\LengthAttributeConverter::class,
+        'letter-spacing'    => \SVG\Reading\LengthAttributeConverter::class,
+        'word-spacing'      => \SVG\Reading\LengthAttributeConverter::class,
     ];
 
     /**
diff --git a/src/Reading/NodeRegistry.php b/src/Reading/NodeRegistry.php
index c4ff1791..04e60fa8 100644
--- a/src/Reading/NodeRegistry.php
+++ b/src/Reading/NodeRegistry.php
@@ -15,74 +15,74 @@ class NodeRegistry
     * @var string[] $nodeTypes Map of tag names to fully-qualified class names.
     */
     private static $nodeTypes = [
-        'foreignObject'         => 'SVG\Nodes\Embedded\SVGForeignObject',
-        'image'                 => 'SVG\Nodes\Embedded\SVGImage',
+        'foreignObject'         => \SVG\Nodes\Embedded\SVGForeignObject::class,
+        'image'                 => \SVG\Nodes\Embedded\SVGImage::class,
 
-        'feBlend'               => 'SVG\Nodes\Filters\SVGFEBlend',
-        'feColorMatrix'         => 'SVG\Nodes\Filters\SVGFEColorMatrix',
-        'feComponentTransfer'   => 'SVG\Nodes\Filters\SVGFEComponentTransfer',
-        'feComposite'           => 'SVG\Nodes\Filters\SVGFEComposite',
-        'feConvolveMatrix'      => 'SVG\Nodes\Filters\SVGFEConvolveMatrix',
-        'feDiffuseLighting'     => 'SVG\Nodes\Filters\SVGFEDiffuseLighting',
-        'feDisplacementMap'     => 'SVG\Nodes\Filters\SVGFEDisplacementMap',
-        'feDistantLight'        => 'SVG\Nodes\Filters\SVGFEDistantLight',
-        'feDropShadow'          => 'SVG\Nodes\Filters\SVGFEDropShadow',
-        'feFlood'               => 'SVG\Nodes\Filters\SVGFEFlood',
-        'feFuncA'               => 'SVG\Nodes\Filters\SVGFEFuncA',
-        'feFuncB'               => 'SVG\Nodes\Filters\SVGFEFuncB',
-        'feFuncG'               => 'SVG\Nodes\Filters\SVGFEFuncG',
-        'feFuncR'               => 'SVG\Nodes\Filters\SVGFEFuncR',
-        'feGaussianBlur'        => 'SVG\Nodes\Filters\SVGFEGaussianBlur',
-        'feImage'               => 'SVG\Nodes\Filters\SVGFEImage',
-        'feMerge'               => 'SVG\Nodes\Filters\SVGFEMerge',
-        'feMergeNode'           => 'SVG\Nodes\Filters\SVGFEMergeNode',
-        'feMorphology'          => 'SVG\Nodes\Filters\SVGFEMorphology',
-        'feOffset'              => 'SVG\Nodes\Filters\SVGFEOffset',
-        'fePointLight'          => 'SVG\Nodes\Filters\SVGFEPointLight',
-        'feSpecularLighting'    => 'SVG\Nodes\Filters\SVGFESpecularLighting',
-        'feSpotLight'           => 'SVG\Nodes\Filters\SVGFESpotLight',
-        'feTile'                => 'SVG\Nodes\Filters\SVGFETile',
-        'feTurbulence'          => 'SVG\Nodes\Filters\SVGFETurbulence',
-        'filter'                => 'SVG\Nodes\Filters\SVGFilter',
+        'feBlend'               => \SVG\Nodes\Filters\SVGFEBlend::class,
+        'feColorMatrix'         => \SVG\Nodes\Filters\SVGFEColorMatrix::class,
+        'feComponentTransfer'   => \SVG\Nodes\Filters\SVGFEComponentTransfer::class,
+        'feComposite'           => \SVG\Nodes\Filters\SVGFEComposite::class,
+        'feConvolveMatrix'      => \SVG\Nodes\Filters\SVGFEConvolveMatrix::class,
+        'feDiffuseLighting'     => \SVG\Nodes\Filters\SVGFEDiffuseLighting::class,
+        'feDisplacementMap'     => \SVG\Nodes\Filters\SVGFEDisplacementMap::class,
+        'feDistantLight'        => \SVG\Nodes\Filters\SVGFEDistantLight::class,
+        'feDropShadow'          => \SVG\Nodes\Filters\SVGFEDropShadow::class,
+        'feFlood'               => \SVG\Nodes\Filters\SVGFEFlood::class,
+        'feFuncA'               => \SVG\Nodes\Filters\SVGFEFuncA::class,
+        'feFuncB'               => \SVG\Nodes\Filters\SVGFEFuncB::class,
+        'feFuncG'               => \SVG\Nodes\Filters\SVGFEFuncG::class,
+        'feFuncR'               => \SVG\Nodes\Filters\SVGFEFuncR::class,
+        'feGaussianBlur'        => \SVG\Nodes\Filters\SVGFEGaussianBlur::class,
+        'feImage'               => \SVG\Nodes\Filters\SVGFEImage::class,
+        'feMerge'               => \SVG\Nodes\Filters\SVGFEMerge::class,
+        'feMergeNode'           => \SVG\Nodes\Filters\SVGFEMergeNode::class,
+        'feMorphology'          => \SVG\Nodes\Filters\SVGFEMorphology::class,
+        'feOffset'              => \SVG\Nodes\Filters\SVGFEOffset::class,
+        'fePointLight'          => \SVG\Nodes\Filters\SVGFEPointLight::class,
+        'feSpecularLighting'    => \SVG\Nodes\Filters\SVGFESpecularLighting::class,
+        'feSpotLight'           => \SVG\Nodes\Filters\SVGFESpotLight::class,
+        'feTile'                => \SVG\Nodes\Filters\SVGFETile::class,
+        'feTurbulence'          => \SVG\Nodes\Filters\SVGFETurbulence::class,
+        'filter'                => \SVG\Nodes\Filters\SVGFilter::class,
 
-        'animate'               => 'SVG\Nodes\Presentation\SVGAnimate',
-        'animateMotion'         => 'SVG\Nodes\Presentation\SVGAnimateMotion',
-        'animateTransform'      => 'SVG\Nodes\Presentation\SVGAnimateTransform',
-        'linearGradient'        => 'SVG\Nodes\Presentation\SVGLinearGradient',
-        'mpath'                 => 'SVG\Nodes\Presentation\SVGMPath',
-        'radialGradient'        => 'SVG\Nodes\Presentation\SVGRadialGradient',
-        'set'                   => 'SVG\Nodes\Presentation\SVGSet',
-        'stop'                  => 'SVG\Nodes\Presentation\SVGStop',
-        'view'                  => 'SVG\Nodes\Presentation\SVGView',
+        'animate'               => \SVG\Nodes\Presentation\SVGAnimate::class,
+        'animateMotion'         => \SVG\Nodes\Presentation\SVGAnimateMotion::class,
+        'animateTransform'      => \SVG\Nodes\Presentation\SVGAnimateTransform::class,
+        'linearGradient'        => \SVG\Nodes\Presentation\SVGLinearGradient::class,
+        'mpath'                 => \SVG\Nodes\Presentation\SVGMPath::class,
+        'radialGradient'        => \SVG\Nodes\Presentation\SVGRadialGradient::class,
+        'set'                   => \SVG\Nodes\Presentation\SVGSet::class,
+        'stop'                  => \SVG\Nodes\Presentation\SVGStop::class,
+        'view'                  => \SVG\Nodes\Presentation\SVGView::class,
 
-        'circle'                => 'SVG\Nodes\Shapes\SVGCircle',
-        'ellipse'               => 'SVG\Nodes\Shapes\SVGEllipse',
-        'line'                  => 'SVG\Nodes\Shapes\SVGLine',
-        'path'                  => 'SVG\Nodes\Shapes\SVGPath',
-        'polygon'               => 'SVG\Nodes\Shapes\SVGPolygon',
-        'polyline'              => 'SVG\Nodes\Shapes\SVGPolyline',
-        'rect'                  => 'SVG\Nodes\Shapes\SVGRect',
+        'circle'                => \SVG\Nodes\Shapes\SVGCircle::class,
+        'ellipse'               => \SVG\Nodes\Shapes\SVGEllipse::class,
+        'line'                  => \SVG\Nodes\Shapes\SVGLine::class,
+        'path'                  => \SVG\Nodes\Shapes\SVGPath::class,
+        'polygon'               => \SVG\Nodes\Shapes\SVGPolygon::class,
+        'polyline'              => \SVG\Nodes\Shapes\SVGPolyline::class,
+        'rect'                  => \SVG\Nodes\Shapes\SVGRect::class,
 
-        'clipPath'              => 'SVG\Nodes\Structures\SVGClipPath',
-        'defs'                  => 'SVG\Nodes\Structures\SVGDefs',
-        'svg'                   => 'SVG\Nodes\Structures\SVGDocumentFragment',
-        'g'                     => 'SVG\Nodes\Structures\SVGGroup',
-        'a'                     => 'SVG\Nodes\Structures\SVGLinkGroup',
-        'marker'                => 'SVG\Nodes\Structures\SVGMarker',
-        'mask'                  => 'SVG\Nodes\Structures\SVGMask',
-        'metadata'              => 'SVG\Nodes\Structures\SVGMetadata',
-        'pattern'               => 'SVG\Nodes\Structures\SVGPattern',
-        'script'                => 'SVG\Nodes\Structures\SVGScript',
-        'style'                 => 'SVG\Nodes\Structures\SVGStyle',
-        'switch'                => 'SVG\Nodes\Structures\SVGSwitch',
-        'symbol'                => 'SVG\Nodes\Structures\SVGSymbol',
-        'use'                   => 'SVG\Nodes\Structures\SVGUse',
+        'clipPath'              => \SVG\Nodes\Structures\SVGClipPath::class,
+        'defs'                  => \SVG\Nodes\Structures\SVGDefs::class,
+        'svg'                   => \SVG\Nodes\Structures\SVGDocumentFragment::class,
+        'g'                     => \SVG\Nodes\Structures\SVGGroup::class,
+        'a'                     => \SVG\Nodes\Structures\SVGLinkGroup::class,
+        'marker'                => \SVG\Nodes\Structures\SVGMarker::class,
+        'mask'                  => \SVG\Nodes\Structures\SVGMask::class,
+        'metadata'              => \SVG\Nodes\Structures\SVGMetadata::class,
+        'pattern'               => \SVG\Nodes\Structures\SVGPattern::class,
+        'script'                => \SVG\Nodes\Structures\SVGScript::class,
+        'style'                 => \SVG\Nodes\Structures\SVGStyle::class,
+        'switch'                => \SVG\Nodes\Structures\SVGSwitch::class,
+        'symbol'                => \SVG\Nodes\Structures\SVGSymbol::class,
+        'use'                   => \SVG\Nodes\Structures\SVGUse::class,
 
-        'desc'                  => 'SVG\Nodes\Texts\SVGDesc',
-        'text'                  => 'SVG\Nodes\Texts\SVGText',
-        'textPath'              => 'SVG\Nodes\Texts\SVGTextPath',
-        'title'                 => 'SVG\Nodes\Texts\SVGTitle',
-        'tspan'                 => 'SVG\Nodes\Texts\SVGTSpan',
+        'desc'                  => \SVG\Nodes\Texts\SVGDesc::class,
+        'text'                  => \SVG\Nodes\Texts\SVGText::class,
+        'textPath'              => \SVG\Nodes\Texts\SVGTextPath::class,
+        'title'                 => \SVG\Nodes\Texts\SVGTitle::class,
+        'tspan'                 => \SVG\Nodes\Texts\SVGTSpan::class,
     ];
 
     /**
diff --git a/src/Utilities/Colors/Color.php b/src/Utilities/Colors/Color.php
index 5186475d..b8c4e9fd 100644
--- a/src/Utilities/Colors/Color.php
+++ b/src/Utilities/Colors/Color.php
@@ -25,11 +25,11 @@ public static function parse(string $color): array
 
         // pass on to dedicated functions depending on notation
         if (preg_match('/^#([0-9A-F]+)$/i', $color, $matches)) {
-            list($r, $g, $b, $a) = self::parseHexComponents($matches[1]);
+            [$r, $g, $b, $a] = self::parseHexComponents($matches[1]);
         } elseif (preg_match('/^rgba?\((.*)\)$/', $color, $matches)) {
-            list($r, $g, $b, $a) = self::parseRGBAComponents($matches[1]);
+            [$r, $g, $b, $a] = self::parseRGBAComponents($matches[1]);
         } elseif (preg_match('/^hsla?\((.*)\)$/', $color, $matches)) {
-            list($r, $g, $b, $a) = self::parseHSLAComponents($matches[1]);
+            [$r, $g, $b, $a] = self::parseHSLAComponents($matches[1]);
         }
 
         // any illegal component invalidates all components
@@ -176,7 +176,7 @@ private static function parseHSLAComponents(string $str): array
         // convert HSL to RGB
         $r = $g = $b = null;
         if (isset($h) && isset($s) && isset($l)) {
-            list($r, $g, $b) = self::convertHSLtoRGB($h, $s, $l);
+            [$r, $g, $b] = self::convertHSLtoRGB($h, $s, $l);
         }
         // add alpha
         $a = count($params) < 4 ? 255 : self::parseRGBAComponent($params[3], 1, 255);
diff --git a/tests/Nodes/Embedded/SVGImageTest.php b/tests/Nodes/Embedded/SVGImageTest.php
index 564f6e93..7a8e5507 100644
--- a/tests/Nodes/Embedded/SVGImageTest.php
+++ b/tests/Nodes/Embedded/SVGImageTest.php
@@ -15,7 +15,7 @@ class SVGImageTest extends \PHPUnit\Framework\TestCase
     /**
      * @covers ::__construct
      */
-    public function test__construct()
+    public function test__construct(): void
     {
         // should not set any attributes by default
         $obj = new SVGImage();
@@ -35,7 +35,7 @@ public function test__construct()
     /**
      * @covers ::getHref
      */
-    public function testGetHref()
+    public function testGetHref(): void
     {
         // should return xlink:href when available
         $obj = new SVGImage();
@@ -56,7 +56,7 @@ public function testGetHref()
     /**
      * @covers ::setHref
      */
-    public function testSetHref()
+    public function testSetHref(): void
     {
         $obj = new SVGImage();
 
@@ -71,7 +71,7 @@ public function testSetHref()
     /**
      * @covers ::getX
      */
-    public function testGetX()
+    public function testGetX(): void
     {
         $obj = new SVGImage();
 
@@ -83,7 +83,7 @@ public function testGetX()
     /**
      * @covers ::setX
      */
-    public function testSetX()
+    public function testSetX(): void
     {
         $obj = new SVGImage();
 
@@ -98,7 +98,7 @@ public function testSetX()
     /**
      * @covers ::getY
      */
-    public function testGetY()
+    public function testGetY(): void
     {
         $obj = new SVGImage();
 
@@ -110,7 +110,7 @@ public function testGetY()
     /**
      * @covers ::setY
      */
-    public function testSetY()
+    public function testSetY(): void
     {
         $obj = new SVGImage();
 
@@ -125,7 +125,7 @@ public function testSetY()
     /**
      * @covers ::getWidth
      */
-    public function testGetWidth()
+    public function testGetWidth(): void
     {
         $obj = new SVGImage();
 
@@ -137,7 +137,7 @@ public function testGetWidth()
     /**
      * @covers ::setWidth
      */
-    public function testSetWidth()
+    public function testSetWidth(): void
     {
         $obj = new SVGImage();
 
@@ -152,7 +152,7 @@ public function testSetWidth()
     /**
      * @covers ::getHeight
      */
-    public function testGetHeight()
+    public function testGetHeight(): void
     {
         $obj = new SVGImage();
 
@@ -164,7 +164,7 @@ public function testGetHeight()
     /**
      * @covers ::setHeight
      */
-    public function testSetHeight()
+    public function testSetHeight(): void
     {
         $obj = new SVGImage();
 
@@ -179,11 +179,11 @@ public function testSetHeight()
     /**
      * @covers ::rasterize
      */
-    public function testRasterize()
+    public function testRasterize(): void
     {
         $obj = new SVGImage('test-href', 10, 10, 100, 100);
 
-        $rast = $this->getMockBuilder('\SVG\Rasterization\SVGRasterizer')
+        $rast = $this->getMockBuilder(\SVG\Rasterization\SVGRasterizer::class)
             ->disableOriginalConstructor()
             ->getMock();
 
diff --git a/tests/Nodes/SVGNodeContainerTest.php b/tests/Nodes/SVGNodeContainerTest.php
index e5c415d0..90c297cf 100644
--- a/tests/Nodes/SVGNodeContainerTest.php
+++ b/tests/Nodes/SVGNodeContainerTest.php
@@ -6,7 +6,7 @@
 
 class SVGNodeContainerSubclass extends SVGNodeContainer
 {
-    const TAG_NAME = 'test_subclass';
+    public const TAG_NAME = 'test_subclass';
 }
 
 /**
@@ -21,7 +21,7 @@ class SVGNodeContainerTest extends \PHPUnit\Framework\TestCase
     /**
      * @covers ::addChild
      */
-    public function testAddChild()
+    public function testAddChild(): void
     {
         $obj = new SVGNodeContainerSubclass();
         $obj2 = new SVGNodeContainerSubclass();
@@ -67,7 +67,7 @@ public function testAddChild()
     /**
      * @covers ::removeChild
      */
-    public function testRemoveChild()
+    public function testRemoveChild(): void
     {
         $obj = new SVGNodeContainerSubclass();
         $child = new SVGNodeContainerSubclass();
@@ -97,7 +97,7 @@ public function testRemoveChild()
     /**
      * @covers ::setChild
      */
-    public function testSetChild()
+    public function testSetChild(): void
     {
         $obj = new SVGNodeContainerSubclass();
         $obj2 = new SVGNodeContainerSubclass();
@@ -129,14 +129,14 @@ public function testSetChild()
     /**
      * @covers ::rasterize
      */
-    public function testRasterize()
+    public function testRasterize(): void
     {
         $obj = new SVGNodeContainerSubclass();
 
-        $mockChild = $this->getMockForAbstractClass('\SVG\Nodes\SVGNode');
+        $mockChild = $this->getMockForAbstractClass(\SVG\Nodes\SVGNode::class);
         $obj->addChild($mockChild);
 
-        $rast = $this->getMockBuilder('\SVG\Rasterization\SVGRasterizer')
+        $rast = $this->getMockBuilder(\SVG\Rasterization\SVGRasterizer::class)
             ->disableOriginalConstructor()
             ->getMock();
 
@@ -152,7 +152,7 @@ public function testRasterize()
     /**
      * @covers ::getElementsByTagName
      */
-    public function testGetElementsByTagName()
+    public function testGetElementsByTagName(): void
     {
         $obj = new SVGNodeContainerSubclass();
         $root_0 = new \SVG\Nodes\Structures\SVGGroup();
@@ -198,7 +198,7 @@ public function testGetElementsByTagName()
     /**
      * @covers ::getElementsByClassName
      */
-    public function testGetElementsByClassName()
+    public function testGetElementsByClassName(): void
     {
         $obj = new SVGNodeContainerSubclass();
         $root_0 = new \SVG\Nodes\Structures\SVGGroup();
@@ -261,11 +261,11 @@ public function testGetElementsByClassName()
     /**
      * @covers ::getContainerStyleForNode
      */
-    public function testGetContainerStyleForNode()
+    public function testGetContainerStyleForNode(): void
     {
         $obj = new SVGNodeContainerSubclass();
 
-        $mockChild = $this->getMockForAbstractClass('\SVG\Nodes\SVGNode');
+        $mockChild = $this->getMockForAbstractClass(\SVG\Nodes\SVGNode::class);
         $obj->addChild($mockChild);
 
         $this->assertCount(0, $obj->getContainerStyleForNode($mockChild));
@@ -274,11 +274,11 @@ public function testGetContainerStyleForNode()
     /**
      * @covers ::getContainerStyleByPattern
      */
-    public function testGetContainerStyleByPattern()
+    public function testGetContainerStyleByPattern(): void
     {
         $obj = new SVGNodeContainerSubclass();
 
-        $mockChild = $this->getMockForAbstractClass('\SVG\Nodes\SVGNode');
+        $mockChild = $this->getMockForAbstractClass(\SVG\Nodes\SVGNode::class);
         $obj->addChild($mockChild);
 
         $this->assertCount(0, $obj->getContainerStyleByPattern('/^(\d+)?\.\d+$/'));
diff --git a/tests/Nodes/SVGNodeTest.php b/tests/Nodes/SVGNodeTest.php
index a32492d1..4329335d 100644
--- a/tests/Nodes/SVGNodeTest.php
+++ b/tests/Nodes/SVGNodeTest.php
@@ -6,7 +6,7 @@
 
 class SVGNodeSubclass extends SVGNode
 {
-    const TAG_NAME = 'test_subclass';
+    public const TAG_NAME = 'test_subclass';
 
     /**
      * @inheritdoc
@@ -28,7 +28,7 @@ class SVGNodeTest extends \PHPUnit\Framework\TestCase
     /**
      * @covers ::getName
      */
-    public function testGetName()
+    public function testGetName(): void
     {
         $obj = new SVGNodeSubclass();
 
@@ -39,7 +39,7 @@ public function testGetName()
     /**
      * @covers ::getParent
      */
-    public function testGetParent()
+    public function testGetParent(): void
     {
         $obj = new SVGNodeSubclass();
 
@@ -50,7 +50,7 @@ public function testGetParent()
     /**
      * @covers ::getValue
      */
-    public function testGetValue()
+    public function testGetValue(): void
     {
         $obj = new SVGNodeSubclass();
 
@@ -61,7 +61,7 @@ public function testGetValue()
     /**
      * @covers ::setValue
      */
-    public function testSetValue()
+    public function testSetValue(): void
     {
         $obj = new SVGNodeSubclass();
 
@@ -80,7 +80,7 @@ public function testSetValue()
     /**
      * @covers ::getStyle
      */
-    public function testGetStyle()
+    public function testGetStyle(): void
     {
         $obj = new SVGNodeSubclass();
 
@@ -91,7 +91,7 @@ public function testGetStyle()
     /**
      * @covers ::setStyle
      */
-    public function testSetStyle()
+    public function testSetStyle(): void
     {
         $obj = new SVGNodeSubclass();
 
@@ -134,7 +134,7 @@ public function testSetStyle()
     /**
      * @covers ::removeStyle
      */
-    public function testRemoveStyle()
+    public function testRemoveStyle(): void
     {
         $obj = new SVGNodeSubclass();
 
@@ -150,7 +150,7 @@ public function testRemoveStyle()
     /**
      * @covers ::getAttribute
      */
-    public function testGetAttribute()
+    public function testGetAttribute(): void
     {
         $obj = new SVGNodeSubclass();
 
@@ -161,7 +161,7 @@ public function testGetAttribute()
     /**
      * @covers ::setAttribute
      */
-    public function testSetAttribute()
+    public function testSetAttribute(): void
     {
         $obj = new SVGNodeSubclass();
 
@@ -193,7 +193,7 @@ public function testSetAttribute()
     /**
      * @covers ::removeAttribute
      */
-    public function testRemoveAttribute()
+    public function testRemoveAttribute(): void
     {
         $obj = new SVGNodeSubclass();
 
@@ -209,7 +209,7 @@ public function testRemoveAttribute()
     /**
      * @covers ::getSerializableNamespaces
      */
-    public function testGetSerializableNamespaces()
+    public function testGetSerializableNamespaces(): void
     {
         $obj = new SVGNodeSubclass();
 
@@ -224,7 +224,7 @@ public function testGetSerializableNamespaces()
     /**
      * @covers ::getSerializableAttributes
      */
-    public function testGetSerializableAttributes()
+    public function testGetSerializableAttributes(): void
     {
         $obj = new SVGNodeSubclass();
 
@@ -242,7 +242,7 @@ public function testGetSerializableAttributes()
     /**
      * @covers ::getSerializableStyles
      */
-    public function testGetSerializableStyles()
+    public function testGetSerializableStyles(): void
     {
         $obj = new SVGNodeSubclass();
 
@@ -258,7 +258,7 @@ public function testGetSerializableStyles()
     /**
      * @covers ::getViewBox
      */
-    public function testGetViewBox()
+    public function testGetViewBox(): void
     {
         $obj = new SVGNodeSubclass();
 
diff --git a/tests/Nodes/Shapes/SVGCircleTest.php b/tests/Nodes/Shapes/SVGCircleTest.php
index f10d34ba..4afd3ba5 100644
--- a/tests/Nodes/Shapes/SVGCircleTest.php
+++ b/tests/Nodes/Shapes/SVGCircleTest.php
@@ -15,7 +15,7 @@ class SVGCircleTest extends \PHPUnit\Framework\TestCase
   /**
      * @covers ::__construct
      */
-    public function test__construct()
+    public function test__construct(): void
     {
         // should not set any attributes by default
         $obj = new SVGCircle();
@@ -33,7 +33,7 @@ public function test__construct()
     /**
      * @covers ::getCenterX
      */
-    public function testGetCenterX()
+    public function testGetCenterX(): void
     {
         $obj = new SVGCircle();
 
@@ -45,7 +45,7 @@ public function testGetCenterX()
     /**
      * @covers ::setCenterX
      */
-    public function testSetCenterX()
+    public function testSetCenterX(): void
     {
         $obj = new SVGCircle();
 
@@ -60,7 +60,7 @@ public function testSetCenterX()
     /**
      * @covers ::getCenterY
      */
-    public function testGetCenterY()
+    public function testGetCenterY(): void
     {
         $obj = new SVGCircle();
 
@@ -72,7 +72,7 @@ public function testGetCenterY()
     /**
      * @covers ::setCenterY
      */
-    public function testSetCenterY()
+    public function testSetCenterY(): void
     {
         $obj = new SVGCircle();
 
@@ -87,7 +87,7 @@ public function testSetCenterY()
     /**
      * @covers ::getRadius
      */
-    public function testGetRadius()
+    public function testGetRadius(): void
     {
         $obj = new SVGCircle();
 
@@ -99,7 +99,7 @@ public function testGetRadius()
     /**
      * @covers ::setRadius
      */
-    public function testSetRadius()
+    public function testSetRadius(): void
     {
         $obj = new SVGCircle();
 
@@ -114,11 +114,11 @@ public function testSetRadius()
     /**
      * @covers ::rasterize
      */
-    public function testRasterize()
+    public function testRasterize(): void
     {
         $obj = new SVGCircle(37, 42, 100);
 
-        $rast = $this->getMockBuilder('\SVG\Rasterization\SVGRasterizer')
+        $rast = $this->getMockBuilder(\SVG\Rasterization\SVGRasterizer::class)
             ->disableOriginalConstructor()
             ->getMock();
 
diff --git a/tests/Nodes/Shapes/SVGEllipseTest.php b/tests/Nodes/Shapes/SVGEllipseTest.php
index ba7903fc..97b516ee 100644
--- a/tests/Nodes/Shapes/SVGEllipseTest.php
+++ b/tests/Nodes/Shapes/SVGEllipseTest.php
@@ -15,7 +15,7 @@ class SVGEllipseTest extends \PHPUnit\Framework\TestCase
     /**
      * @covers ::__construct
      */
-    public function test__construct()
+    public function test__construct(): void
     {
         // should not set any attributes by default
         $obj = new SVGEllipse();
@@ -34,7 +34,7 @@ public function test__construct()
     /**
      * @covers ::getCenterX
      */
-    public function testGetCenterX()
+    public function testGetCenterX(): void
     {
         $obj = new SVGEllipse();
 
@@ -46,7 +46,7 @@ public function testGetCenterX()
     /**
      * @covers ::setCenterX
      */
-    public function testSetCenterX()
+    public function testSetCenterX(): void
     {
         $obj = new SVGEllipse();
 
@@ -61,7 +61,7 @@ public function testSetCenterX()
     /**
      * @covers ::getCenterY
      */
-    public function testGetCenterY()
+    public function testGetCenterY(): void
     {
         $obj = new SVGEllipse();
 
@@ -73,7 +73,7 @@ public function testGetCenterY()
     /**
      * @covers ::setCenterY
      */
-    public function testSetCenterY()
+    public function testSetCenterY(): void
     {
         $obj = new SVGEllipse();
 
@@ -88,7 +88,7 @@ public function testSetCenterY()
     /**
      * @covers ::getRadiusX
      */
-    public function testGetRadiusX()
+    public function testGetRadiusX(): void
     {
         $obj = new SVGEllipse();
 
@@ -100,7 +100,7 @@ public function testGetRadiusX()
     /**
      * @covers ::setRadiusX
      */
-    public function testSetRadiusX()
+    public function testSetRadiusX(): void
     {
         $obj = new SVGEllipse();
 
@@ -115,7 +115,7 @@ public function testSetRadiusX()
     /**
      * @covers ::getRadiusY
      */
-    public function testGetRadiusY()
+    public function testGetRadiusY(): void
     {
         $obj = new SVGEllipse();
 
@@ -127,7 +127,7 @@ public function testGetRadiusY()
     /**
      * @covers ::setRadiusY
      */
-    public function testSetRadiusY()
+    public function testSetRadiusY(): void
     {
         $obj = new SVGEllipse();
 
@@ -142,11 +142,11 @@ public function testSetRadiusY()
     /**
      * @covers ::rasterize
      */
-    public function testRasterize()
+    public function testRasterize(): void
     {
         $obj = new SVGEllipse(37, 42, 100, 200);
 
-        $rast = $this->getMockBuilder('\SVG\Rasterization\SVGRasterizer')
+        $rast = $this->getMockBuilder(\SVG\Rasterization\SVGRasterizer::class)
             ->disableOriginalConstructor()
             ->getMock();
 
diff --git a/tests/Nodes/Shapes/SVGLineTest.php b/tests/Nodes/Shapes/SVGLineTest.php
index d5160bf7..a52be623 100644
--- a/tests/Nodes/Shapes/SVGLineTest.php
+++ b/tests/Nodes/Shapes/SVGLineTest.php
@@ -15,7 +15,7 @@ class SVGLineTest extends \PHPUnit\Framework\TestCase
     /**
      * @covers ::__construct
      */
-    public function test__construct()
+    public function test__construct(): void
     {
         // should not set any attributes by default
         $obj = new SVGLine();
@@ -34,7 +34,7 @@ public function test__construct()
     /**
      * @covers ::getX1
      */
-    public function testGetX1()
+    public function testGetX1(): void
     {
         $obj = new SVGLine();
 
@@ -46,7 +46,7 @@ public function testGetX1()
     /**
      * @covers ::setX1
      */
-    public function testSetX1()
+    public function testSetX1(): void
     {
         $obj = new SVGLine();
 
@@ -61,7 +61,7 @@ public function testSetX1()
     /**
      * @covers ::getY1
      */
-    public function testGetY1()
+    public function testGetY1(): void
     {
         $obj = new SVGLine();
 
@@ -73,7 +73,7 @@ public function testGetY1()
     /**
      * @covers ::setY1
      */
-    public function testSetY1()
+    public function testSetY1(): void
     {
         $obj = new SVGLine();
 
@@ -88,7 +88,7 @@ public function testSetY1()
     /**
      * @covers ::getX2
      */
-    public function testGetX2()
+    public function testGetX2(): void
     {
         $obj = new SVGLine();
 
@@ -100,7 +100,7 @@ public function testGetX2()
     /**
      * @covers ::setX2
      */
-    public function testSetX2()
+    public function testSetX2(): void
     {
         $obj = new SVGLine();
 
@@ -115,7 +115,7 @@ public function testSetX2()
     /**
      * @covers ::getY2
      */
-    public function testGetY2()
+    public function testGetY2(): void
     {
         $obj = new SVGLine();
 
@@ -127,7 +127,7 @@ public function testGetY2()
     /**
      * @covers ::setY2
      */
-    public function testSetY2()
+    public function testSetY2(): void
     {
         $obj = new SVGLine();
 
@@ -142,11 +142,11 @@ public function testSetY2()
     /**
      * @covers ::rasterize
      */
-    public function testRasterize()
+    public function testRasterize(): void
     {
         $obj = new SVGLine(11, 12, 13, 14);
 
-        $rast = $this->getMockBuilder('\SVG\Rasterization\SVGRasterizer')
+        $rast = $this->getMockBuilder(\SVG\Rasterization\SVGRasterizer::class)
             ->disableOriginalConstructor()
             ->getMock();
 
diff --git a/tests/Nodes/Shapes/SVGPathTest.php b/tests/Nodes/Shapes/SVGPathTest.php
index a41284e0..565fdff9 100644
--- a/tests/Nodes/Shapes/SVGPathTest.php
+++ b/tests/Nodes/Shapes/SVGPathTest.php
@@ -24,7 +24,7 @@ class SVGPathTest extends \PHPUnit\Framework\TestCase
     /**
      * @covers ::__construct
      */
-    public function test__construct()
+    public function test__construct(): void
     {
         // should not set any attributes by default
         $obj = new SVGPath();
@@ -40,7 +40,7 @@ public function test__construct()
     /**
      * @covers ::getDescription
      */
-    public function testGetDescription()
+    public function testGetDescription(): void
     {
         $obj = new SVGPath();
 
@@ -52,7 +52,7 @@ public function testGetDescription()
     /**
      * @covers ::setDescription
      */
-    public function testSetDescription()
+    public function testSetDescription(): void
     {
         $obj = new SVGPath();
 
@@ -67,11 +67,11 @@ public function testSetDescription()
     /**
      * @covers ::rasterize
      */
-    public function testRasterizeWithNull()
+    public function testRasterizeWithNull(): void
     {
         $obj = new SVGPath();
 
-        $rast = $this->getMockBuilder('\SVG\Rasterization\SVGRasterizer')
+        $rast = $this->getMockBuilder(\SVG\Rasterization\SVGRasterizer::class)
             ->disableOriginalConstructor()
             ->getMock();
 
@@ -83,12 +83,12 @@ public function testRasterizeWithNull()
     /**
      * @covers ::rasterize
      */
-    public function testRasterize()
+    public function testRasterize(): void
     {
         $obj = new SVGPath(self::$sampleDescription);
 
         // setup mocks
-        $rast = $this->getMockBuilder('\SVG\Rasterization\SVGRasterizer')
+        $rast = $this->getMockBuilder(\SVG\Rasterization\SVGRasterizer::class)
             ->disableOriginalConstructor()
             ->getMock();
 
@@ -118,7 +118,7 @@ public function testRasterize()
     /**
      * @covers ::rasterize
      */
-    public function testRasterizeShouldRespectFillRule()
+    public function testRasterizeShouldRespectFillRule(): void
     {
         $obj = new SVGPath(self::$sampleDescription);
 
@@ -134,7 +134,7 @@ public function testRasterizeShouldRespectFillRule()
             'foo' => 'foo',
         ];
         foreach ($attributeToExpectedFillRule as $attribute => $expectedFillRule) {
-            $rasterizer = $this->getMockBuilder('\SVG\Rasterization\SVGRasterizer')
+            $rasterizer = $this->getMockBuilder(\SVG\Rasterization\SVGRasterizer::class)
                 ->disableOriginalConstructor()
                 ->getMock();
 
diff --git a/tests/Nodes/Shapes/SVGPolygonTest.php b/tests/Nodes/Shapes/SVGPolygonTest.php
index 3d23d29c..d0ea770a 100644
--- a/tests/Nodes/Shapes/SVGPolygonTest.php
+++ b/tests/Nodes/Shapes/SVGPolygonTest.php
@@ -15,7 +15,7 @@ class SVGPolygonTest extends \PHPUnit\Framework\TestCase
     /**
      * @covers ::__construct
      */
-    public function test__construct()
+    public function test__construct(): void
     {
         // should set empty points by default
         $obj = new SVGPolygon();
@@ -33,7 +33,7 @@ public function test__construct()
     /**
      * @covers ::rasterize
      */
-    public function testRasterize()
+    public function testRasterize(): void
     {
         $points = [
             [42.5, 42.5],
@@ -42,7 +42,7 @@ public function testRasterize()
 
         $obj = new SVGPolygon($points);
 
-        $rast = $this->getMockBuilder('\SVG\Rasterization\SVGRasterizer')
+        $rast = $this->getMockBuilder(\SVG\Rasterization\SVGRasterizer::class)
             ->disableOriginalConstructor()
             ->getMock();
 
@@ -73,7 +73,7 @@ public function testRasterize()
     /**
      * @covers ::rasterize
      */
-    public function testRasterizeShouldRespectFillRule()
+    public function testRasterizeShouldRespectFillRule(): void
     {
         $points = [
             [42.5, 42.5],
@@ -94,7 +94,7 @@ public function testRasterizeShouldRespectFillRule()
             'foo' => 'foo',
         ];
         foreach ($attributeToExpectedFillRule as $attribute => $expectedFillRule) {
-            $rasterizer = $this->getMockBuilder('\SVG\Rasterization\SVGRasterizer')
+            $rasterizer = $this->getMockBuilder(\SVG\Rasterization\SVGRasterizer::class)
                 ->disableOriginalConstructor()
                 ->getMock();
 
diff --git a/tests/Nodes/Shapes/SVGPolygonalShapeTest.php b/tests/Nodes/Shapes/SVGPolygonalShapeTest.php
index 63339ad5..26b0b5af 100644
--- a/tests/Nodes/Shapes/SVGPolygonalShapeTest.php
+++ b/tests/Nodes/Shapes/SVGPolygonalShapeTest.php
@@ -9,7 +9,7 @@
  */
 class SVGPolygonalShapeSubclass extends SVGPolygonalShape
 {
-    const TAG_NAME = 'test_subclass';
+    public const TAG_NAME = 'test_subclass';
 
     public function __construct(array $points = null)
     {
@@ -32,7 +32,7 @@ class SVGPolygonalShapeTest extends \PHPUnit\Framework\TestCase
     /**
      * @covers ::__construct
      */
-    public function test__construct()
+    public function test__construct(): void
     {
         // should not set attribute if nothing is provided
         $obj = new SVGPolygonalShapeSubclass();
@@ -62,7 +62,7 @@ public function test__construct()
     /**
      * @covers ::addPoint
      */
-    public function testAddPoint()
+    public function testAddPoint(): void
     {
         $obj = new SVGPolygonalShapeSubclass();
 
@@ -91,7 +91,7 @@ public function testAddPoint()
     /**
      * @covers ::removePoint
      */
-    public function testRemovePoint()
+    public function testRemovePoint(): void
     {
         $obj = new SVGPolygonalShapeSubclass([
             [42.5, 43.5],
@@ -121,7 +121,7 @@ public function testRemovePoint()
     /**
      * @covers ::countPoints
      */
-    public function testCountPoints()
+    public function testCountPoints(): void
     {
         $obj = new SVGPolygonalShapeSubclass([
             [42.5, 43.5],
@@ -155,7 +155,7 @@ public function testCountPoints()
     /**
      * @covers ::getPoints
      */
-    public function testGetPoints()
+    public function testGetPoints(): void
     {
         $obj = new SVGPolygonalShapeSubclass();
 
@@ -187,7 +187,7 @@ public function testGetPoints()
     /**
      * @covers ::getPoint
      */
-    public function testGetPoint()
+    public function testGetPoint(): void
     {
         $obj = new SVGPolygonalShapeSubclass([
             [42.5, 43.5],
@@ -202,7 +202,7 @@ public function testGetPoint()
     /**
      * @covers ::setPoint
      */
-    public function testSetPoint()
+    public function testSetPoint(): void
     {
         $obj = new SVGPolygonalShapeSubclass([
             [42.5, 43.5],
diff --git a/tests/Nodes/Shapes/SVGPolylineTest.php b/tests/Nodes/Shapes/SVGPolylineTest.php
index cfa139ef..8313a4db 100644
--- a/tests/Nodes/Shapes/SVGPolylineTest.php
+++ b/tests/Nodes/Shapes/SVGPolylineTest.php
@@ -15,7 +15,7 @@ class SVGPolylineTest extends \PHPUnit\Framework\TestCase
     /**
      * @covers ::__construct
      */
-    public function test__construct()
+    public function test__construct(): void
     {
         // should set empty points by default
         $obj = new SVGPolyline();
@@ -33,7 +33,7 @@ public function test__construct()
     /**
      * @covers ::rasterize
      */
-    public function testRasterize()
+    public function testRasterize(): void
     {
         $points = [
             [42.5, 42.5],
@@ -42,7 +42,7 @@ public function testRasterize()
 
         $obj = new SVGPolyline($points);
 
-        $rast = $this->getMockBuilder('\SVG\Rasterization\SVGRasterizer')
+        $rast = $this->getMockBuilder(\SVG\Rasterization\SVGRasterizer::class)
             ->disableOriginalConstructor()
             ->getMock();
 
@@ -73,7 +73,7 @@ public function testRasterize()
     /**
      * @covers ::rasterize
      */
-    public function testRasterizeShouldRespectFillRule()
+    public function testRasterizeShouldRespectFillRule(): void
     {
         $points = [
             [42.5, 42.5],
@@ -94,7 +94,7 @@ public function testRasterizeShouldRespectFillRule()
             'foo' => 'foo',
         ];
         foreach ($attributeToExpectedFillRule as $attribute => $expectedFillRule) {
-            $rasterizer = $this->getMockBuilder('\SVG\Rasterization\SVGRasterizer')
+            $rasterizer = $this->getMockBuilder(\SVG\Rasterization\SVGRasterizer::class)
                 ->disableOriginalConstructor()
                 ->getMock();
 
diff --git a/tests/Nodes/Shapes/SVGRectTest.php b/tests/Nodes/Shapes/SVGRectTest.php
index f24b92c2..1f56a75a 100644
--- a/tests/Nodes/Shapes/SVGRectTest.php
+++ b/tests/Nodes/Shapes/SVGRectTest.php
@@ -15,7 +15,7 @@ class SVGRectTest extends \PHPUnit\Framework\TestCase
     /**
      * @covers ::__construct
      */
-    public function test__construct()
+    public function test__construct(): void
     {
         // should not set any attributes by default
         $obj = new SVGRect();
@@ -34,7 +34,7 @@ public function test__construct()
     /**
      * @covers ::getX
      */
-    public function testGetX()
+    public function testGetX(): void
     {
         $obj = new SVGRect();
 
@@ -46,7 +46,7 @@ public function testGetX()
     /**
      * @covers ::setX
      */
-    public function testSetX()
+    public function testSetX(): void
     {
         $obj = new SVGRect();
 
@@ -61,7 +61,7 @@ public function testSetX()
     /**
      * @covers ::getY
      */
-    public function testGetY()
+    public function testGetY(): void
     {
         $obj = new SVGRect();
 
@@ -73,7 +73,7 @@ public function testGetY()
     /**
      * @covers ::setY
      */
-    public function testSetY()
+    public function testSetY(): void
     {
         $obj = new SVGRect();
 
@@ -88,7 +88,7 @@ public function testSetY()
     /**
      * @covers ::getWidth
      */
-    public function testGetWidth()
+    public function testGetWidth(): void
     {
         $obj = new SVGRect();
 
@@ -100,7 +100,7 @@ public function testGetWidth()
     /**
      * @covers ::setWidth
      */
-    public function testSetWidth()
+    public function testSetWidth(): void
     {
         $obj = new SVGRect();
 
@@ -115,7 +115,7 @@ public function testSetWidth()
     /**
      * @covers ::getHeight
      */
-    public function testGetHeight()
+    public function testGetHeight(): void
     {
         $obj = new SVGRect();
 
@@ -127,7 +127,7 @@ public function testGetHeight()
     /**
      * @covers ::setHeight
      */
-    public function testSetHeight()
+    public function testSetHeight(): void
     {
         $obj = new SVGRect();
 
@@ -142,7 +142,7 @@ public function testSetHeight()
     /**
      * @covers ::getRX
      */
-    public function testGetRX()
+    public function testGetRX(): void
     {
         $obj = new SVGRect();
 
@@ -154,7 +154,7 @@ public function testGetRX()
     /**
      * @covers ::setRX
      */
-    public function testSetRX()
+    public function testSetRX(): void
     {
         $obj = new SVGRect();
 
@@ -169,7 +169,7 @@ public function testSetRX()
     /**
      * @covers ::getRY
      */
-    public function testGetRY()
+    public function testGetRY(): void
     {
         $obj = new SVGRect();
 
@@ -181,7 +181,7 @@ public function testGetRY()
     /**
      * @covers ::setRY
      */
-    public function testSetRY()
+    public function testSetRY(): void
     {
         $obj = new SVGRect();
 
@@ -196,13 +196,13 @@ public function testSetRY()
     /**
      * @covers ::rasterize
      */
-    public function testRasterize()
+    public function testRasterize(): void
     {
         $obj = new SVGRect(37, 42, 100, 200);
         $obj->setAttribute('rx', 15);
         $obj->setAttribute('ry', 25);
 
-        $rast = $this->getMockBuilder('\SVG\Rasterization\SVGRasterizer')
+        $rast = $this->getMockBuilder(\SVG\Rasterization\SVGRasterizer::class)
             ->disableOriginalConstructor()
             ->getMock();
 
diff --git a/tests/Nodes/Structures/SVGDefsTest.php b/tests/Nodes/Structures/SVGDefsTest.php
index 00a6e166..08256b9d 100644
--- a/tests/Nodes/Structures/SVGDefsTest.php
+++ b/tests/Nodes/Structures/SVGDefsTest.php
@@ -15,7 +15,7 @@ class SVGDefsTest extends \PHPUnit\Framework\TestCase
     /**
      * @covers ::__construct
      */
-    public function test__construct()
+    public function test__construct(): void
     {
         // should not set any attributes by default
         $obj = new SVGDefs();
@@ -25,14 +25,14 @@ public function test__construct()
     /**
      * @covers ::rasterize
      */
-    public function testRasterize()
+    public function testRasterize(): void
     {
         $obj = new SVGDefs();
 
-        $mockChild = $this->getMockForAbstractClass('\SVG\Nodes\SVGNode');
+        $mockChild = $this->getMockForAbstractClass(\SVG\Nodes\SVGNode::class);
         $obj->addChild($mockChild);
 
-        $rast = $this->getMockBuilder('\SVG\Rasterization\SVGRasterizer')
+        $rast = $this->getMockBuilder(\SVG\Rasterization\SVGRasterizer::class)
             ->disableOriginalConstructor()
             ->getMock();
 
diff --git a/tests/Nodes/Structures/SVGDocumentFragmentTest.php b/tests/Nodes/Structures/SVGDocumentFragmentTest.php
index 7deba0a5..540280f2 100644
--- a/tests/Nodes/Structures/SVGDocumentFragmentTest.php
+++ b/tests/Nodes/Structures/SVGDocumentFragmentTest.php
@@ -16,7 +16,7 @@ class SVGDocumentFragmentTest extends \PHPUnit\Framework\TestCase
     /**
      * @covers ::__construct
      */
-    public function test__construct()
+    public function test__construct(): void
     {
         $container = new \SVG\Nodes\Structures\SVGGroup();
 
@@ -34,7 +34,7 @@ public function test__construct()
     /**
      * @covers ::isRoot
      */
-    public function testIsRoot()
+    public function testIsRoot(): void
     {
         // should return true by default
         $obj = new SVGDocumentFragment();
@@ -49,7 +49,7 @@ public function testIsRoot()
     /**
      * @covers ::getWidth
      */
-    public function testGetWidth()
+    public function testGetWidth(): void
     {
         $obj = new SVGDocumentFragment();
 
@@ -61,7 +61,7 @@ public function testGetWidth()
     /**
      * @covers ::setWidth
      */
-    public function testSetWidth()
+    public function testSetWidth(): void
     {
         $obj = new SVGDocumentFragment();
 
@@ -76,7 +76,7 @@ public function testSetWidth()
     /**
      * @covers ::getHeight
      */
-    public function testGetHeight()
+    public function testGetHeight(): void
     {
         $obj = new SVGDocumentFragment();
 
@@ -88,7 +88,7 @@ public function testGetHeight()
     /**
      * @covers ::setHeight
      */
-    public function testSetHeight()
+    public function testSetHeight(): void
     {
         $obj = new SVGDocumentFragment();
 
@@ -103,7 +103,7 @@ public function testSetHeight()
     /**
      * @covers ::getComputedStyle
      */
-    public function testGetComputedStyle()
+    public function testGetComputedStyle(): void
     {
         $obj = new SVGDocumentFragment();
 
@@ -125,7 +125,7 @@ public function testGetComputedStyle()
     /**
      * @covers ::getSerializableNamespaces
      */
-    public function testGetSerializableNamespaces()
+    public function testGetSerializableNamespaces(): void
     {
         // should include 'xmlns' and 'xmlns:xlink' namespaces for root
         $obj = new SVGDocumentFragment();
@@ -161,7 +161,7 @@ public function testGetSerializableNamespaces()
     /**
      * @covers ::getSerializableAttributes
      */
-    public function testGetSerializableAttributes()
+    public function testGetSerializableAttributes(): void
     {
         $container = new \SVG\Nodes\Structures\SVGGroup();
 
@@ -196,7 +196,7 @@ public function testGetSerializableAttributes()
     /**
      * @covers ::getElementById
      */
-    public function testGetElementById()
+    public function testGetElementById(): void
     {
         // should return null if not found
         $obj = new SVGDocumentFragment();
@@ -211,14 +211,14 @@ public function testGetElementById()
         $obj = new SVGDocumentFragment();
         $obj->addChild(
             // <container>
-            $this->getMockForAbstractClass('\SVG\Nodes\SVGNodeContainer')->addChild(
+            $this->getMockForAbstractClass(\SVG\Nodes\SVGNodeContainer::class)->addChild(
                 // <node />
-                $this->getMockForAbstractClass('\SVG\Nodes\SVGNode')
+                $this->getMockForAbstractClass(\SVG\Nodes\SVGNode::class)
             )->addChild(
                 // <container>
-                $this->getMockForAbstractClass('\SVG\Nodes\SVGNodeContainer')->addChild(
+                $this->getMockForAbstractClass(\SVG\Nodes\SVGNodeContainer::class)->addChild(
                     // <node id="foobar" />
-                    $expected = $this->getMockForAbstractClass('\SVG\Nodes\SVGNode')
+                    $expected = $this->getMockForAbstractClass(\SVG\Nodes\SVGNode::class)
                         ->setAttribute('id', 'foobar')
                 )
                 // </container>
@@ -227,9 +227,9 @@ public function testGetElementById()
         );
         $obj->addChild(
             // <container>
-            $this->getMockForAbstractClass('\SVG\Nodes\SVGNodeContainer')->addChild(
+            $this->getMockForAbstractClass(\SVG\Nodes\SVGNodeContainer::class)->addChild(
                 // <node id="foobar" />
-                $this->getMockForAbstractClass('\SVG\Nodes\SVGNode')
+                $this->getMockForAbstractClass(\SVG\Nodes\SVGNode::class)
                     ->setAttribute('id', 'foobar')
             )
             // </container>
@@ -243,7 +243,7 @@ public function testGetElementById()
      * @requires extension gd
      * @coversNothing
      */
-    public function testRasterize_empty()
+    public function testRasterize_empty(): void
     {
         $obj = new SVGDocumentFragment('2px', '2px');
 
@@ -264,7 +264,7 @@ public function testRasterize_empty()
      * @requires extension gd
      * @coversNothing
      */
-    public function testRasterize_object_unscaled()
+    public function testRasterize_object_unscaled(): void
     {
         $obj = new SVGDocumentFragment('20px', '40px');
 
@@ -289,7 +289,7 @@ public function testRasterize_object_unscaled()
      * @requires extension gd
      * @coversNothing
      */
-    public function testRasterize_object_scaledUp()
+    public function testRasterize_object_scaledUp(): void
     {
         $obj = new SVGDocumentFragment('10px', '20px');
 
@@ -314,7 +314,7 @@ public function testRasterize_object_scaledUp()
      * @requires extension gd
      * @coversNothing
      */
-    public function testRasterize_object_scaledDown()
+    public function testRasterize_object_scaledDown(): void
     {
         $obj = new SVGDocumentFragment('40px', '80px');
 
@@ -339,7 +339,7 @@ public function testRasterize_object_scaledDown()
      * @requires extension gd
      * @coversNothing
      */
-    public function testRasterize_object_viewBox()
+    public function testRasterize_object_viewBox(): void
     {
         $obj = new SVGDocumentFragment('100%', '100%');
         $obj->setAttribute('viewBox', '100 100 2 4');
diff --git a/tests/Nodes/Structures/SVGScriptTest.php b/tests/Nodes/Structures/SVGScriptTest.php
index 4b4ba884..1a9f21d9 100644
--- a/tests/Nodes/Structures/SVGScriptTest.php
+++ b/tests/Nodes/Structures/SVGScriptTest.php
@@ -14,7 +14,7 @@ class SVGScriptTest extends \PHPUnit\Framework\TestCase
     /**
      * @covers ::__construct
      */
-    public function test__construct()
+    public function test__construct(): void
     {
         // should default to empty CSS, type = text/css
         $obj = new SVGScript();
@@ -28,11 +28,11 @@ public function test__construct()
     /**
      * @covers ::rasterize
      */
-    public function testRasterize()
+    public function testRasterize(): void
     {
         $obj = new SVGScript();
 
-        $rast = $this->getMockBuilder('\SVG\Rasterization\SVGRasterizer')
+        $rast = $this->getMockBuilder(\SVG\Rasterization\SVGRasterizer::class)
             ->disableOriginalConstructor()
             ->getMock();
 
diff --git a/tests/Nodes/Structures/SVGStyleTest.php b/tests/Nodes/Structures/SVGStyleTest.php
index 161d30ac..15fb73e3 100644
--- a/tests/Nodes/Structures/SVGStyleTest.php
+++ b/tests/Nodes/Structures/SVGStyleTest.php
@@ -14,7 +14,7 @@ class SVGStyleTest extends \PHPUnit\Framework\TestCase
     /**
      * @covers ::__construct
      */
-    public function test__construct()
+    public function test__construct(): void
     {
         // should default to empty CSS, type = text/css
         $obj = new SVGStyle();
@@ -30,7 +30,7 @@ public function test__construct()
     /**
      * @covers ::getType
      */
-    public function testGetType()
+    public function testGetType(): void
     {
         $obj = new SVGStyle();
         $obj->setAttribute('type', 'test-type');
@@ -41,10 +41,10 @@ public function testGetType()
     /**
      * @covers ::setType
      */
-    public function testSetType()
+    public function testSetType(): void
     {
         $obj = new SVGStyle();
-        $this->assertInstanceOf('SVG\Nodes\Structures\SVGStyle', $obj->setType('test-type'));
+        $this->assertInstanceOf(\SVG\Nodes\Structures\SVGStyle::class, $obj->setType('test-type'));
 
         $this->assertEquals('test-type', $obj->getAttribute('type'));
 
@@ -54,11 +54,11 @@ public function testSetType()
     /**
      * @covers ::rasterize
      */
-    public function testRasterize()
+    public function testRasterize(): void
     {
         $obj = new SVGStyle();
 
-        $rast = $this->getMockBuilder('\SVG\Rasterization\SVGRasterizer')
+        $rast = $this->getMockBuilder(\SVG\Rasterization\SVGRasterizer::class)
             ->disableOriginalConstructor()
             ->getMock();
 
diff --git a/tests/Nodes/Texts/SVGTextTest.php b/tests/Nodes/Texts/SVGTextTest.php
index b0f38b10..9dc59f98 100644
--- a/tests/Nodes/Texts/SVGTextTest.php
+++ b/tests/Nodes/Texts/SVGTextTest.php
@@ -15,13 +15,13 @@ class SVGTextTest extends \PHPUnit\Framework\TestCase
     /**
      * @covers ::rasterize
      */
-    public function testRasterizeShouldHaveDefaultFontSize()
+    public function testRasterizeShouldHaveDefaultFontSize(): void
     {
         // Test for https://github.com/meyfa/php-svg/issues/195
 
         $obj = new SVGText('foo', 10, 10);
 
-        $rast = $this->getMockBuilder('\SVG\Rasterization\SVGRasterizer')
+        $rast = $this->getMockBuilder(\SVG\Rasterization\SVGRasterizer::class)
             ->disableOriginalConstructor()
             ->getMock();
 
diff --git a/tests/Rasterization/Path/ArcApproximatorTest.php b/tests/Rasterization/Path/ArcApproximatorTest.php
index 75efdbea..2c03ee69 100644
--- a/tests/Rasterization/Path/ArcApproximatorTest.php
+++ b/tests/Rasterization/Path/ArcApproximatorTest.php
@@ -11,7 +11,7 @@
  */
 class ArcApproximatorTest extends \PHPUnit\Framework\TestCase
 {
-    public function testApproximate()
+    public function testApproximate(): void
     {
         $approx = new ArcApproximator();
         $p0 = [10.5, 10.5];
@@ -27,7 +27,7 @@ public function testApproximate()
         $this->assertCount(0, $result);
     }
 
-    public function testApproximateWithXaIsLessThanZero()
+    public function testApproximateWithXaIsLessThanZero(): void
     {
         $approx = new ArcApproximator();
         $p0 = [10.5, 10.5];
@@ -43,7 +43,7 @@ public function testApproximateWithXaIsLessThanZero()
         $this->assertCount(0, $result);
     }
 
-    public function testApproximateWithRxAndRyAreZero()
+    public function testApproximateWithRxAndRyAreZero(): void
     {
         $approx = new ArcApproximator();
         $p0 = [10.5, 10.5];
@@ -62,7 +62,7 @@ public function testApproximateWithRxAndRyAreZero()
         $this->assertSame(10.6, $result[1][1]);
     }
 
-    public function testApproximateWithRxAndRyAreNotZero()
+    public function testApproximateWithRxAndRyAreNotZero(): void
     {
         $approx = new ArcApproximator();
         $p0 = [10.5, 10.5];
@@ -83,7 +83,7 @@ public function testApproximateWithRxAndRyAreNotZero()
         $this->assertEqualsWithDelta(10.6, $result[2][1], 10e-12);
     }
 
-    public function testApproximateFlags()
+    public function testApproximateFlags(): void
     {
         $approx = new ArcApproximator();
         $p0 = [10, 10];
@@ -122,7 +122,7 @@ public function testApproximateFlags()
         $this->assertEqualsWithDelta(-8.65, $result[count($result) / 2][1], 0.5);
     }
 
-    public function testApproximateRadiusScaling()
+    public function testApproximateRadiusScaling(): void
     {
         $approx = new ArcApproximator();
         $p0 = [10, 10];
diff --git a/tests/Rasterization/Path/BezierApproximatorTest.php b/tests/Rasterization/Path/BezierApproximatorTest.php
index 6a105abe..d88197f5 100644
--- a/tests/Rasterization/Path/BezierApproximatorTest.php
+++ b/tests/Rasterization/Path/BezierApproximatorTest.php
@@ -11,7 +11,7 @@
  */
 class BezierApproximatorTest extends \PHPUnit\Framework\TestCase
 {
-    public function testQuadratic()
+    public function testQuadratic(): void
     {
         $bezier = new BezierApproximator();
         $p0 = [20, 10];
@@ -26,7 +26,7 @@ public function testQuadratic()
         $this->assertEqualsWithDelta(20, $result[$n - 1][1], 1);
     }
 
-    public function testCubic()
+    public function testCubic(): void
     {
         $bezier = new BezierApproximator();
         $p0 = [20, 10];
diff --git a/tests/Rasterization/Path/PathApproximatorTest.php b/tests/Rasterization/Path/PathApproximatorTest.php
index 41992958..e5eb851e 100644
--- a/tests/Rasterization/Path/PathApproximatorTest.php
+++ b/tests/Rasterization/Path/PathApproximatorTest.php
@@ -14,7 +14,7 @@ class PathApproximatorTest extends \PHPUnit\Framework\TestCase
 {
     // general tests
 
-    public function testApproximate()
+    public function testApproximate(): void
     {
         $approx = new PathApproximator(Transform::identity());
         $cmds = [
@@ -35,7 +35,7 @@ public function testApproximate()
         ], $result);
     }
 
-    public function testApproximateWithTransform()
+    public function testApproximateWithTransform(): void
     {
         $transform = Transform::identity();
         $transform->scale(3, 5);
@@ -59,7 +59,7 @@ public function testApproximateWithTransform()
         ], $result);
     }
 
-    public function testApproximateStopsAtInvalidCommand()
+    public function testApproximateStopsAtInvalidCommand(): void
     {
         $approx = new PathApproximator(Transform::identity());
         $cmds = [
@@ -82,7 +82,7 @@ public function testApproximateStopsAtInvalidCommand()
 
     // tests more specific to each path command
 
-    public function testMoveTo()
+    public function testMoveTo(): void
     {
         // https://www.w3.org/TR/SVG/paths.html#PathDataMovetoCommands
         // "A path data segment (if there is one) must begin with a "moveto" command."
@@ -106,7 +106,7 @@ public function testMoveTo()
         $this->assertSame([], $approx->getSubpaths());
     }
 
-    public function testLineTo()
+    public function testLineTo(): void
     {
         $approx = new PathApproximator(Transform::identity());
         $approx->approximate([
@@ -155,7 +155,7 @@ public function testLineTo()
         ], $approx->getSubpaths());
     }
 
-    public function testLineToHorizontal()
+    public function testLineToHorizontal(): void
     {
         $approx = new PathApproximator(Transform::identity());
         $approx->approximate([
@@ -190,7 +190,7 @@ public function testLineToHorizontal()
         ], $approx->getSubpaths());
     }
 
-    public function testLineToVertical()
+    public function testLineToVertical(): void
     {
         $approx = new PathApproximator(Transform::identity());
         $approx->approximate([
@@ -225,7 +225,7 @@ public function testLineToVertical()
         ], $approx->getSubpaths());
     }
 
-    public function testCurveToCubic()
+    public function testCurveToCubic(): void
     {
         // Simple test: draw cubic curves representing straight lines
         $approx = new PathApproximator(Transform::identity());
@@ -249,16 +249,16 @@ public function testCurveToCubic()
         $this->assertLessThan(0.6 * count($subpaths[0]), $corner);
         // expect everything before to be a straight horizontal line
         for ($i = 1; $i <= $corner; ++$i) {
-            list($xPrev, $yPrev) = $subpaths[0][$i - 1];
-            list($x, $y) = $subpaths[0][$i];
+            [$xPrev, $yPrev] = $subpaths[0][$i - 1];
+            [$x, $y] = $subpaths[0][$i];
             $this->assertGreaterThanOrEqual($xPrev, $x);
             $this->assertLessThanOrEqual(20, $x);
             $this->assertEquals($yPrev, $y);
         }
         // expect everything after to be a straight vertical line
         for ($i = $corner + 1; $i < count($subpaths[0]); ++$i) {
-            list($xPrev, $yPrev) = $subpaths[0][$i - 1];
-            list($x, $y) = $subpaths[0][$i];
+            [$xPrev, $yPrev] = $subpaths[0][$i - 1];
+            [$x, $y] = $subpaths[0][$i];
             $this->assertEquals($xPrev, $x);
             $this->assertGreaterThanOrEqual($yPrev, $y);
             $this->assertLessThanOrEqual(30, $y);
@@ -278,7 +278,7 @@ public function testCurveToCubic()
         $this->assertLessThan(4.5 * count($subpaths[0]), count($subpaths2[0]));
     }
 
-    public function testCurveToCubicSmooth()
+    public function testCurveToCubicSmooth(): void
     {
         // without preceding CurveToCubic
         $approx = new PathApproximator(Transform::identity());
@@ -293,7 +293,7 @@ public function testCurveToCubicSmooth()
         $this->assertEquals([10, 20], $subpaths[0][0]);
         $this->assertEquals([20, 20], $subpaths[0][count($subpaths[0]) - 1]);
         // check center (the curve should bend downwards about halfway to the only control point)
-        list($x, $y) = $subpaths[0][ceil(count($subpaths[0]) / 2)];
+        [$x, $y] = $subpaths[0][ceil(count($subpaths[0]) / 2)];
         $this->assertEqualsWithDelta(15, $x, 1.0);
         $this->assertEqualsWithDelta(25, $y, 1.0);
 
@@ -313,20 +313,20 @@ public function testCurveToCubicSmooth()
         $this->assertEquals([30, 20], $subpaths[0][count($subpaths[0]) - 1]);
         // The curve should first bend down due to 'C', then bend up due to the reflected 's'.
         // - check at 1/4 from beginning
-        list($x, $y) = $subpaths[0][ceil(count($subpaths[0]) * 0.25)];
+        [$x, $y] = $subpaths[0][ceil(count($subpaths[0]) * 0.25)];
         $this->assertEqualsWithDelta(15, $x, 1.0);
         $this->assertEqualsWithDelta(27.5, $y, 1.0);
         // - check at 1/2 from beginning
-        list($x, $y) = $subpaths[0][ceil(count($subpaths[0]) * 0.5)];
+        [$x, $y] = $subpaths[0][ceil(count($subpaths[0]) * 0.5)];
         $this->assertEqualsWithDelta(20, $x, 1.0);
         $this->assertEqualsWithDelta(20, $y, 1.0);
         // - check at 3/4 from beginning
-        list($x, $y) = $subpaths[0][ceil(count($subpaths[0]) * 0.75)];
+        [$x, $y] = $subpaths[0][ceil(count($subpaths[0]) * 0.75)];
         $this->assertEqualsWithDelta(25, $x, 1.0);
         $this->assertEqualsWithDelta(12.5, $y, 1.0);
     }
 
-    public function testCurveToQuadratic()
+    public function testCurveToQuadratic(): void
     {
         // Simple test: draw quadratic curves representing straight lines
         $approx = new PathApproximator(Transform::identity());
@@ -350,16 +350,16 @@ public function testCurveToQuadratic()
         $this->assertLessThan(0.6 * count($subpaths[0]), $corner);
         // expect everything before to be a straight horizontal line
         for ($i = 1; $i <= $corner; ++$i) {
-            list($xPrev, $yPrev) = $subpaths[0][$i - 1];
-            list($x, $y) = $subpaths[0][$i];
+            [$xPrev, $yPrev] = $subpaths[0][$i - 1];
+            [$x, $y] = $subpaths[0][$i];
             $this->assertGreaterThanOrEqual($xPrev, $x);
             $this->assertLessThanOrEqual(20, $x);
             $this->assertEqualsWithDelta($yPrev, $y, 10e-12);
         }
         // expect everything after to be a straight vertical line
         for ($i = $corner + 1; $i < count($subpaths[0]); ++$i) {
-            list($xPrev, $yPrev) = $subpaths[0][$i - 1];
-            list($x, $y) = $subpaths[0][$i];
+            [$xPrev, $yPrev] = $subpaths[0][$i - 1];
+            [$x, $y] = $subpaths[0][$i];
             $this->assertEqualsWithDelta($xPrev, $x, 10e-12);
             $this->assertGreaterThanOrEqual($yPrev, $y);
             $this->assertLessThanOrEqual(30, $y);
@@ -379,7 +379,7 @@ public function testCurveToQuadratic()
         $this->assertLessThan(4.5 * count($subpaths[0]), count($subpaths2[0]));
     }
 
-    public function testCurveToQuadraticSmooth()
+    public function testCurveToQuadraticSmooth(): void
     {
         // without preceding CurveToQuadratic
         $approx = new PathApproximator(Transform::identity());
@@ -394,7 +394,7 @@ public function testCurveToQuadraticSmooth()
         $this->assertEquals([10, 20], $subpaths[0][0]);
         $this->assertEquals([20, 20], $subpaths[0][count($subpaths[0]) - 1]);
         // check center (the curve should represent a flat horizontal line)
-        list($x, $y) = $subpaths[0][ceil(count($subpaths[0]) / 2)];
+        [$x, $y] = $subpaths[0][ceil(count($subpaths[0]) / 2)];
         $this->assertEqualsWithDelta(15, $x, 1.0);
         $this->assertEqualsWithDelta(20, $y, 1.0);
 
@@ -414,20 +414,20 @@ public function testCurveToQuadraticSmooth()
         $this->assertEquals([30, 20], $subpaths[0][count($subpaths[0]) - 1]);
         // The curve should first bend down due to 'Q', then bend up due to the reflected 't'.
         // - check at 1/4 from beginning
-        list($x, $y) = $subpaths[0][ceil(count($subpaths[0]) * 0.25)];
+        [$x, $y] = $subpaths[0][ceil(count($subpaths[0]) * 0.25)];
         $this->assertEqualsWithDelta(15, $x, 1.0);
         $this->assertEqualsWithDelta(25, $y, 1.0);
         // - check at 1/2 from beginning
-        list($x, $y) = $subpaths[0][ceil(count($subpaths[0]) * 0.5)];
+        [$x, $y] = $subpaths[0][ceil(count($subpaths[0]) * 0.5)];
         $this->assertEqualsWithDelta(20, $x, 1.0);
         $this->assertEqualsWithDelta(20, $y, 1.0);
         // - check at 3/4 from beginning
-        list($x, $y) = $subpaths[0][ceil(count($subpaths[0]) * 0.75)];
+        [$x, $y] = $subpaths[0][ceil(count($subpaths[0]) * 0.75)];
         $this->assertEqualsWithDelta(25, $x, 1.0);
         $this->assertEqualsWithDelta(15, $y, 1.0);
     }
 
-    public function testArcTo()
+    public function testArcTo(): void
     {
         // Run the following test once for the absolute command and once for the relative command.
         // The coordinates are chosen so that the output should be equal.
@@ -449,14 +449,14 @@ public function testArcTo()
             $this->assertEquals([20, 20], $subpaths[0][count($subpaths[0]) - 1]);
             // points in between should have x >= 10 && x <= 20 and y >= 20, y <= 30
             foreach ($subpaths[0] as $point) {
-                list($x, $y) = $point;
+                [$x, $y] = $point;
                 $this->assertGreaterThanOrEqual(10, $x);
                 $this->assertLessThanOrEqual(20, $x);
                 $this->assertGreaterThanOrEqual(20, $y);
                 $this->assertLessThanOrEqual(30, $y);
             }
             // midpoint should roughly be at [15, 30]
-            list($x, $y) = $subpaths[0][ceil(count($subpaths[0]) / 2)];
+            [$x, $y] = $subpaths[0][ceil(count($subpaths[0]) / 2)];
             $this->assertEqualsWithDelta(15, $x, 0.5);
             $this->assertEqualsWithDelta(30, $y, 0.5);
         }
@@ -474,7 +474,7 @@ public function testArcTo()
         $this->assertLessThan(4.5 * count($subpaths[0]), count($subpaths2[0]));
     }
 
-    public function testClosePath()
+    public function testClosePath(): void
     {
         // try with both 'z' and 'Z', which should behave the same
         foreach (['z', 'Z'] as $closeCommand) {
diff --git a/tests/Rasterization/Path/PathParserTest.php b/tests/Rasterization/Path/PathParserTest.php
index 5d213274..b1a1992f 100644
--- a/tests/Rasterization/Path/PathParserTest.php
+++ b/tests/Rasterization/Path/PathParserTest.php
@@ -11,7 +11,7 @@
  */
 class PathParserTest extends \PHPUnit\Framework\TestCase
 {
-    public function testShouldSplitCorrectly()
+    public function testShouldSplitCorrectly(): void
     {
         $obj = new PathParser();
 
@@ -29,7 +29,7 @@ public function testShouldSplitCorrectly()
         ], $obj->parse(' M10,10 l +10 -10 h .5e2 v 100e-1 l7-7 h.5 z H0z'));
     }
 
-    public function testShouldSupportRepeatedCommands()
+    public function testShouldSupportRepeatedCommands(): void
     {
         $obj = new PathParser();
 
@@ -45,7 +45,7 @@ public function testShouldSupportRepeatedCommands()
         ], $obj->parse('L10,10 20,20 h 5 5 5 q 10 10 20 20 50 50 60 60'));
     }
 
-    public function testShouldTreatImplicitMoveToLikeLineTo()
+    public function testShouldTreatImplicitMoveToLikeLineTo(): void
     {
         $obj = new PathParser();
 
@@ -59,7 +59,7 @@ public function testShouldTreatImplicitMoveToLikeLineTo()
         ], $obj->parse('M10,10 20,20, 20,10 m-10,0 -10,-5'));
     }
 
-    public function testShouldAbortOnError()
+    public function testShouldAbortOnError(): void
     {
         $obj = new PathParser();
 
diff --git a/tests/Rasterization/Path/PolygonBuilderTest.php b/tests/Rasterization/Path/PolygonBuilderTest.php
index 19d86971..9d1bb6e8 100644
--- a/tests/Rasterization/Path/PolygonBuilderTest.php
+++ b/tests/Rasterization/Path/PolygonBuilderTest.php
@@ -15,7 +15,7 @@ class PolygonBuilderTest extends \PHPUnit\Framework\TestCase
     /**
      * @covers ::__construct
      */
-    public function test__construct()
+    public function test__construct(): void
     {
         // should set position to origin by default
         $obj = new PolygonBuilder();
@@ -29,7 +29,7 @@ public function test__construct()
     /**
      * @covers ::build
      */
-    public function testBuild()
+    public function testBuild(): void
     {
         // should return an array of float 2-tuples
         $obj = new PolygonBuilder();
@@ -44,7 +44,7 @@ public function testBuild()
     /**
      * @covers ::getFirstPoint
      */
-    public function testGetFirstPoint()
+    public function testGetFirstPoint(): void
     {
         $obj = new PolygonBuilder();
 
@@ -60,7 +60,7 @@ public function testGetFirstPoint()
     /**
      * @covers ::getLastPoint
      */
-    public function testGetLastPoint()
+    public function testGetLastPoint(): void
     {
         $obj = new PolygonBuilder();
 
@@ -76,7 +76,7 @@ public function testGetLastPoint()
     /**
      * @covers ::getPosition
      */
-    public function testGetPosition()
+    public function testGetPosition(): void
     {
         $obj = new PolygonBuilder(10, 20);
 
@@ -91,7 +91,7 @@ public function testGetPosition()
     /**
      * @covers ::addPoint
      */
-    public function testAddPoint()
+    public function testAddPoint(): void
     {
         $obj = new PolygonBuilder();
 
@@ -120,7 +120,7 @@ public function testAddPoint()
     /**
      * @covers ::addPointRelative
      */
-    public function testAddPointRelative()
+    public function testAddPointRelative(): void
     {
         $obj = new PolygonBuilder();
 
@@ -147,7 +147,7 @@ public function testAddPointRelative()
     /**
      * @covers ::addPoints
      */
-    public function testAddPoints()
+    public function testAddPoints(): void
     {
         $obj = new PolygonBuilder();
 
diff --git a/tests/Rasterization/Renderers/ImageRendererTest.php b/tests/Rasterization/Renderers/ImageRendererTest.php
index e9ecc628..901226c4 100644
--- a/tests/Rasterization/Renderers/ImageRendererTest.php
+++ b/tests/Rasterization/Renderers/ImageRendererTest.php
@@ -9,7 +9,7 @@
 
 class SVGNodeClass extends SVGNode
 {
-    const TAG_NAME = 'test_subclass';
+    public const TAG_NAME = 'test_subclass';
 
     /**
      * @inheritdoc
@@ -27,7 +27,7 @@ public function rasterize(\SVG\Rasterization\SVGRasterizer $rasterizer): void
  */
 class ImageRendererTest extends \PHPUnit\Framework\TestCase
 {
-    public function testRender()
+    public function testRender(): void
     {
         $obj = new ImageRenderer();
 
@@ -46,7 +46,7 @@ public function testRender()
         $this->assertThat($img, new GDSimilarityConstraint('./tests/images/renderer-image.png'));
     }
 
-    public function testDefaultsXAndYToZero()
+    public function testDefaultsXAndYToZero(): void
     {
         $obj = new ImageRenderer();
 
diff --git a/tests/Rasterization/Renderers/MultiPassRendererTest.php b/tests/Rasterization/Renderers/MultiPassRendererTest.php
index a62983f4..e9fd2d33 100644
--- a/tests/Rasterization/Renderers/MultiPassRendererTest.php
+++ b/tests/Rasterization/Renderers/MultiPassRendererTest.php
@@ -33,30 +33,30 @@ private function isGdImage()
         }
     }
 
-    public function testRenderShouldCallPrepare()
+    public function testRenderShouldCallPrepare(): void
     {
         $rasterizer = new \SVG\Rasterization\SVGRasterizer(10, 20, null, 100, 200);
-        $node = $this->getMockForAbstractClass('\SVG\Nodes\SVGNode');
+        $node = $this->getMockForAbstractClass(\SVG\Nodes\SVGNode::class);
 
         // should call prepareRenderParams with correct arguments
-        $obj = $this->getMockForAbstractClass('\SVG\Rasterization\Renderers\MultiPassRenderer');
+        $obj = $this->getMockForAbstractClass(\SVG\Rasterization\Renderers\MultiPassRenderer::class);
         $obj->expects($this->once())->method('prepareRenderParams')->with(
             $this->identicalTo(self::$sampleOptions),
-            $this->isInstanceOf('\SVG\Rasterization\Transform\Transform')
+            $this->isInstanceOf(\SVG\Rasterization\Transform\Transform::class)
         )->willReturn(self::$sampleParams);
         $obj->render($rasterizer, self::$sampleOptions, $node);
 
         imagedestroy($rasterizer->getImage());
     }
 
-    public function testRenderShouldCallRenderFill()
+    public function testRenderShouldCallRenderFill(): void
     {
         $rasterizer = new \SVG\Rasterization\SVGRasterizer(10, 20, null, 100, 200);
-        $node = $this->getMockForAbstractClass('\SVG\Nodes\SVGNode');
+        $node = $this->getMockForAbstractClass(\SVG\Nodes\SVGNode::class);
 
         // should call renderFill with correct fill color
         $node->setStyle('fill', '#AAAAAA');
-        $obj = $this->getMockForAbstractClass('\SVG\Rasterization\Renderers\MultiPassRenderer');
+        $obj = $this->getMockForAbstractClass(\SVG\Rasterization\Renderers\MultiPassRenderer::class);
         $obj->method('prepareRenderParams')->willReturn(self::$sampleParams);
         $obj->expects($this->once())->method('renderFill')->with(
             $this->isGdImage(),
@@ -67,7 +67,7 @@ public function testRenderShouldCallRenderFill()
 
         // should not call renderFill with 'fill: none' style
         $node->setStyle('fill', 'none');
-        $obj = $this->getMockForAbstractClass('\SVG\Rasterization\Renderers\MultiPassRenderer');
+        $obj = $this->getMockForAbstractClass(\SVG\Rasterization\Renderers\MultiPassRenderer::class);
         $obj->method('prepareRenderParams')->willReturn(self::$sampleParams);
         $obj->expects($this->never())->method('renderFill');
         $obj->render($rasterizer, self::$sampleOptions, $node);
@@ -75,15 +75,15 @@ public function testRenderShouldCallRenderFill()
         imagedestroy($rasterizer->getImage());
     }
 
-    public function testRenderShouldCallRenderStroke()
+    public function testRenderShouldCallRenderStroke(): void
     {
         $rasterizer = new \SVG\Rasterization\SVGRasterizer(10, 20, null, 100, 200);
-        $node = $this->getMockForAbstractClass('\SVG\Nodes\SVGNode');
+        $node = $this->getMockForAbstractClass(\SVG\Nodes\SVGNode::class);
 
         // should call renderStroke with correct stroke color and width
         $node->setStyle('stroke', '#BBBBBB');
         $node->setStyle('stroke-width', '2px');
-        $obj = $this->getMockForAbstractClass('\SVG\Rasterization\Renderers\MultiPassRenderer');
+        $obj = $this->getMockForAbstractClass(\SVG\Rasterization\Renderers\MultiPassRenderer::class);
         $obj->method('prepareRenderParams')->willReturn(self::$sampleParams);
         $obj->expects($this->once())->method('renderStroke')->with(
             $this->isGdImage(),
@@ -95,7 +95,7 @@ public function testRenderShouldCallRenderStroke()
 
         // should not call renderStroke with 'stroke: none' style
         $node->setStyle('stroke', 'none');
-        $obj = $this->getMockForAbstractClass('\SVG\Rasterization\Renderers\MultiPassRenderer');
+        $obj = $this->getMockForAbstractClass(\SVG\Rasterization\Renderers\MultiPassRenderer::class);
         $obj->method('prepareRenderParams')->willReturn(self::$sampleParams);
         $obj->expects($this->never())->method('renderStroke');
         $obj->render($rasterizer, self::$sampleOptions, $node);
@@ -103,16 +103,16 @@ public function testRenderShouldCallRenderStroke()
         imagedestroy($rasterizer->getImage());
     }
 
-    public function testRenderShouldRespectFillOpacity()
+    public function testRenderShouldRespectFillOpacity(): void
     {
         $rasterizer = new \SVG\Rasterization\SVGRasterizer(10, 20, null, 100, 200);
-        $node = $this->getMockForAbstractClass('\SVG\Nodes\SVGNode');
+        $node = $this->getMockForAbstractClass(\SVG\Nodes\SVGNode::class);
 
         // should use fill-opacity for the alpha value (try with a few different notations)
         foreach (['0.5', '.5', '50%', '  0.5  ', '  50%  '] as $fillOpacity) {
             $node->setStyle('fill', '#AAAAAA');
             $node->setStyle('fill-opacity', $fillOpacity);
-            $obj = $this->getMockForAbstractClass('\SVG\Rasterization\Renderers\MultiPassRenderer');
+            $obj = $this->getMockForAbstractClass(\SVG\Rasterization\Renderers\MultiPassRenderer::class);
             $obj->method('prepareRenderParams')->willReturn(self::$sampleParams);
             $obj->expects($this->once())->method('renderFill')->with(
                 $this->isGdImage(),
@@ -125,17 +125,17 @@ public function testRenderShouldRespectFillOpacity()
         imagedestroy($rasterizer->getImage());
     }
 
-    public function testRenderShouldRespectStrokeOpacity()
+    public function testRenderShouldRespectStrokeOpacity(): void
     {
         $rasterizer = new \SVG\Rasterization\SVGRasterizer(10, 20, null, 100, 200);
-        $node = $this->getMockForAbstractClass('\SVG\Nodes\SVGNode');
+        $node = $this->getMockForAbstractClass(\SVG\Nodes\SVGNode::class);
 
         // should use stroke-opacity for the alpha value (try with a few different notations)
         foreach (['0.5', '.5', '50%', '  0.5  ', '  50%  '] as $strokeOpacity) {
             $node->setStyle('stroke', '#BBBBBB');
             $node->setStyle('stroke-opacity', $strokeOpacity);
             $node->setStyle('stroke-width', '2px');
-            $obj = $this->getMockForAbstractClass('\SVG\Rasterization\Renderers\MultiPassRenderer');
+            $obj = $this->getMockForAbstractClass(\SVG\Rasterization\Renderers\MultiPassRenderer::class);
             $obj->method('prepareRenderParams')->willReturn(self::$sampleParams);
             $obj->expects($this->once())->method('renderStroke')->with(
                 $this->isGdImage(),
diff --git a/tests/Rasterization/Renderers/PolygonRendererTest.php b/tests/Rasterization/Renderers/PolygonRendererTest.php
index 378df1fe..1daabf48 100644
--- a/tests/Rasterization/Renderers/PolygonRendererTest.php
+++ b/tests/Rasterization/Renderers/PolygonRendererTest.php
@@ -14,7 +14,7 @@
  */
 class PolygonRendererTest extends \PHPUnit\Framework\TestCase
 {
-    public function testShouldNotFailForTooFewPoints()
+    public function testShouldNotFailForTooFewPoints(): void
     {
         // ensures that there is no crash in case fewer than 3 points are provided,
         // which might trip up the fill or stroke algorithms if they don't check for it
@@ -22,7 +22,7 @@ public function testShouldNotFailForTooFewPoints()
 
         $obj = new PolygonRenderer();
 
-        $context = $this->getMockForAbstractClass('\SVG\Nodes\SVGNode');
+        $context = $this->getMockForAbstractClass(\SVG\Nodes\SVGNode::class);
         $context->setStyle('fill', '#FF0000');
         $context->setStyle('stroke', '#0000FF');
         $context->setStyle('stroke-width', '1px');
@@ -51,11 +51,11 @@ public function testShouldNotFailForTooFewPoints()
         ], $context);
     }
 
-    public function testShouldRespectFillRule()
+    public function testShouldRespectFillRule(): void
     {
         $obj = new PolygonRenderer();
 
-        $context = $this->getMockForAbstractClass('\SVG\Nodes\SVGNode');
+        $context = $this->getMockForAbstractClass(\SVG\Nodes\SVGNode::class);
         $context->setStyle('fill', '#FF0000');
         $context->setStyle('stroke', 'none');
 
diff --git a/tests/Rasterization/Renderers/RectRendererTest.php b/tests/Rasterization/Renderers/RectRendererTest.php
index 518e7402..7d0b921a 100644
--- a/tests/Rasterization/Renderers/RectRendererTest.php
+++ b/tests/Rasterization/Renderers/RectRendererTest.php
@@ -14,11 +14,11 @@
  */
 class RectRendererTest extends \PHPUnit\Framework\TestCase
 {
-    public function testShouldRenderStroke()
+    public function testShouldRenderStroke(): void
     {
         $obj = new RectRenderer();
 
-        $context = $this->getMockForAbstractClass('\SVG\Nodes\SVGNode');
+        $context = $this->getMockForAbstractClass(\SVG\Nodes\SVGNode::class);
         $context->setStyle('fill', 'none');
         $context->setStyle('stroke', '#FF0000');
         $context->setStyle('stroke-width', '1px');
@@ -33,11 +33,11 @@ public function testShouldRenderStroke()
         $this->assertThat($img, new GDSimilarityConstraint('./tests/images/renderer-rect-stroke.png'));
     }
 
-    public function testShouldRenderStrokeThick()
+    public function testShouldRenderStrokeThick(): void
     {
         $obj = new RectRenderer();
 
-        $context = $this->getMockForAbstractClass('\SVG\Nodes\SVGNode');
+        $context = $this->getMockForAbstractClass(\SVG\Nodes\SVGNode::class);
         $context->setStyle('fill', 'none');
         $context->setStyle('stroke', '#FF0000');
         $context->setStyle('stroke-width', '3px');
@@ -52,11 +52,11 @@ public function testShouldRenderStrokeThick()
         $this->assertThat($img, new GDSimilarityConstraint('./tests/images/renderer-rect-stroke-thick.png'));
     }
 
-    public function testShouldRenderStrokeAlpha()
+    public function testShouldRenderStrokeAlpha(): void
     {
         $obj = new RectRenderer();
 
-        $context = $this->getMockForAbstractClass('\SVG\Nodes\SVGNode');
+        $context = $this->getMockForAbstractClass(\SVG\Nodes\SVGNode::class);
         $context->setStyle('fill', 'none');
         $context->setStyle('stroke', 'rgba(255, 0, 0, 0.5)');
         $context->setStyle('stroke-width', '3px');
@@ -71,11 +71,11 @@ public function testShouldRenderStrokeAlpha()
         $this->assertThat($img, new GDSimilarityConstraint('./tests/images/renderer-rect-stroke-alpha.png'));
     }
 
-    public function testShouldRenderFill()
+    public function testShouldRenderFill(): void
     {
         $obj = new RectRenderer();
 
-        $context = $this->getMockForAbstractClass('\SVG\Nodes\SVGNode');
+        $context = $this->getMockForAbstractClass(\SVG\Nodes\SVGNode::class);
         $context->setStyle('fill', '#FF0000');
         $context->setStyle('stroke', 'none');
 
@@ -89,11 +89,11 @@ public function testShouldRenderFill()
         $this->assertThat($img, new GDSimilarityConstraint('./tests/images/renderer-rect-fill.png'));
     }
 
-    public function testShouldRenderFillAlpha()
+    public function testShouldRenderFillAlpha(): void
     {
         $obj = new RectRenderer();
 
-        $context = $this->getMockForAbstractClass('\SVG\Nodes\SVGNode');
+        $context = $this->getMockForAbstractClass(\SVG\Nodes\SVGNode::class);
         $context->setStyle('fill', 'rgba(255, 0, 0, 0.5)');
         $context->setStyle('stroke', 'none');
 
@@ -107,11 +107,11 @@ public function testShouldRenderFillAlpha()
         $this->assertThat($img, new GDSimilarityConstraint('./tests/images/renderer-rect-fill-alpha.png'));
     }
 
-    public function testShouldRenderStrokeAndFill()
+    public function testShouldRenderStrokeAndFill(): void
     {
         $obj = new RectRenderer();
 
-        $context = $this->getMockForAbstractClass('\SVG\Nodes\SVGNode');
+        $context = $this->getMockForAbstractClass(\SVG\Nodes\SVGNode::class);
         $context->setStyle('fill', 'rgba(255, 255, 255, 0.5)');
         $context->setStyle('stroke', 'rgba(0, 0, 0, 0.5)');
         $context->setStyle('stroke-width', '5px');
@@ -126,11 +126,11 @@ public function testShouldRenderStrokeAndFill()
         $this->assertThat($img, new GDSimilarityConstraint('./tests/images/renderer-rect-stroke-fill.png'));
     }
 
-    public function testShouldRenderStrokeRounded()
+    public function testShouldRenderStrokeRounded(): void
     {
         $obj = new RectRenderer();
 
-        $context = $this->getMockForAbstractClass('\SVG\Nodes\SVGNode');
+        $context = $this->getMockForAbstractClass(\SVG\Nodes\SVGNode::class);
         $context->setStyle('fill', 'none');
         $context->setStyle('stroke', '#FF0000');
         $context->setStyle('stroke-width', '1px');
@@ -146,11 +146,11 @@ public function testShouldRenderStrokeRounded()
         $this->assertThat($img, new GDSimilarityConstraint('./tests/images/renderer-rect-stroke-rounded.png'));
     }
 
-    public function testShouldRenderFillRounded()
+    public function testShouldRenderFillRounded(): void
     {
         $obj = new RectRenderer();
 
-        $context = $this->getMockForAbstractClass('\SVG\Nodes\SVGNode');
+        $context = $this->getMockForAbstractClass(\SVG\Nodes\SVGNode::class);
         $context->setStyle('fill', '#FF0000');
         $context->setStyle('stroke', 'none');
 
@@ -165,11 +165,11 @@ public function testShouldRenderFillRounded()
         $this->assertThat($img, new GDSimilarityConstraint('./tests/images/renderer-rect-fill-rounded.png'));
     }
 
-    public function testDoesNotRenderIfWidthZero()
+    public function testDoesNotRenderIfWidthZero(): void
     {
         $obj = new RectRenderer();
 
-        $context = $this->getMockForAbstractClass('\SVG\Nodes\SVGNode');
+        $context = $this->getMockForAbstractClass(\SVG\Nodes\SVGNode::class);
         $context->setStyle('fill', '#FF0000');
         $context->setStyle('stroke', '#0000FF');
         $context->setStyle('stroke-width', '1px');
@@ -185,11 +185,11 @@ public function testDoesNotRenderIfWidthZero()
         $this->assertThat($img, new GDSimilarityConstraint('./tests/images/renderer-rect-empty.png'));
     }
 
-    public function testDoesNotRenderIfHeightZero()
+    public function testDoesNotRenderIfHeightZero(): void
     {
         $obj = new RectRenderer();
 
-        $context = $this->getMockForAbstractClass('\SVG\Nodes\SVGNode');
+        $context = $this->getMockForAbstractClass(\SVG\Nodes\SVGNode::class);
         $context->setStyle('fill', '#FF0000');
         $context->setStyle('stroke', '#0000FF');
         $context->setStyle('stroke-width', '1px');
@@ -205,11 +205,11 @@ public function testDoesNotRenderIfHeightZero()
         $this->assertThat($img, new GDSimilarityConstraint('./tests/images/renderer-rect-empty.png'));
     }
 
-    public function testDefaultsXAndYToZero()
+    public function testDefaultsXAndYToZero(): void
     {
         $obj = new RectRenderer();
 
-        $context = $this->getMockForAbstractClass('\SVG\Nodes\SVGNode');
+        $context = $this->getMockForAbstractClass(\SVG\Nodes\SVGNode::class);
         $context->setStyle('fill', '#FFFFFF');
         $context->setStyle('stroke', '#000000');
         $context->setStyle('stroke-width', '5px');
diff --git a/tests/Rasterization/Renderers/TextRendererTest.php b/tests/Rasterization/Renderers/TextRendererTest.php
index 88a6ef6c..d4d85e58 100644
--- a/tests/Rasterization/Renderers/TextRendererTest.php
+++ b/tests/Rasterization/Renderers/TextRendererTest.php
@@ -13,11 +13,11 @@
  */
 class TextRendererTest extends \PHPUnit\Framework\TestCase
 {
-    public function testShouldNotFailWithoutRegisteredFont()
+    public function testShouldNotFailWithoutRegisteredFont(): void
     {
         $obj = new TextRenderer();
 
-        $context = $this->getMockForAbstractClass('\SVG\Nodes\SVGNode');
+        $context = $this->getMockForAbstractClass(\SVG\Nodes\SVGNode::class);
 
         $rasterizer = new SVGRasterizer('40px', '80px', null, 4, 8);
         $obj->render($rasterizer, [
diff --git a/tests/Rasterization/SVGRasterizerTest.php b/tests/Rasterization/SVGRasterizerTest.php
index 87d48a9b..1f3945bb 100644
--- a/tests/Rasterization/SVGRasterizerTest.php
+++ b/tests/Rasterization/SVGRasterizerTest.php
@@ -18,7 +18,7 @@ class SVGRasterizerTest extends \PHPUnit\Framework\TestCase
     /**
      * @covers ::getDocumentWidth
      */
-    public function testGetDocumentWidth()
+    public function testGetDocumentWidth(): void
     {
         // should return parsed unit relative to target size
         $obj = new SVGRasterizer('50%', '50%', null, 100, 200);
@@ -34,7 +34,7 @@ public function testGetDocumentWidth()
     /**
      * @covers ::getDocumentHeight
      */
-    public function testGetDocumentHeight()
+    public function testGetDocumentHeight(): void
     {
         // should return parsed unit relative to target size
         $obj = new SVGRasterizer('50%', '50%', null, 100, 200);
@@ -50,7 +50,7 @@ public function testGetDocumentHeight()
     /**
      * @covers ::getNormalizedDiagonal
      */
-    public function testGetNormalizedDiagonal()
+    public function testGetNormalizedDiagonal(): void
     {
         // should return the correct length
         $obj = new SVGRasterizer('50%', '50%', null, 100, 200);
@@ -61,7 +61,7 @@ public function testGetNormalizedDiagonal()
     /**
      * @covers ::getWidth
      */
-    public function testGetWidth()
+    public function testGetWidth(): void
     {
         // should return the constructor parameter
         $obj = new SVGRasterizer(10, 20, null, 100, 200);
@@ -72,7 +72,7 @@ public function testGetWidth()
     /**
      * @covers ::getHeight
      */
-    public function testGetHeight()
+    public function testGetHeight(): void
     {
         // should return the constructor parameter
         $obj = new SVGRasterizer(10, 20, null, 100, 200);
@@ -83,7 +83,7 @@ public function testGetHeight()
     /**
      * @covers ::getDiagonalScale
      */
-    public function testGetDiagonalScale()
+    public function testGetDiagonalScale(): void
     {
         // should use viewBox dimension when available
         $obj = new SVGRasterizer(10, 20, [37, 42, 25, 100], 100, 200);
@@ -100,7 +100,7 @@ public function testGetDiagonalScale()
     /**
      * @covers ::getViewbox
      */
-    public function testGetViewbox()
+    public function testGetViewbox(): void
     {
         // should return the constructor parameter
         $obj = new SVGRasterizer(10, 20, [37, 42, 25, 100], 100, 200);
@@ -116,7 +116,7 @@ public function testGetViewbox()
     /**
      * @covers ::getImage
      */
-    public function testGetImage()
+    public function testGetImage(): void
     {
         $obj = new SVGRasterizer(10, 20, [], 100, 200);
 
@@ -139,7 +139,7 @@ public function testGetImage()
     /**
      * @covers ::getCurrentTransform
      */
-    public function testGetCurrentTransform()
+    public function testGetCurrentTransform(): void
     {
         // should use viewBox dimension when available
         $obj = new SVGRasterizer(10, 20, [37, 42, 25, 80], 100, 160);
@@ -164,7 +164,7 @@ public function testGetCurrentTransform()
      * @covers ::pushTransform
      * @covers ::popTransform
      */
-    public function testTransformStack()
+    public function testTransformStack(): void
     {
         $obj = new SVGRasterizer(10, 20, [37, 42, 25, 80], 100, 160);
 
@@ -206,19 +206,19 @@ public function testTransformStack()
     /**
      * @covers ::render
      */
-    public function testRenderWithNoSuchRenderId()
+    public function testRenderWithNoSuchRenderId(): void
     {
         $this->expectException('\InvalidArgumentException');
 
         $obj = new SVGRasterizer(10, 20, [], 100, 200);
-        $mockChild = $this->getMockForAbstractClass('\SVG\Nodes\SVGNode');
+        $mockChild = $this->getMockForAbstractClass(\SVG\Nodes\SVGNode::class);
         $obj->render('invalid_render_id', ['option' => 'value'], $mockChild);
     }
 
     /**
      * @covers \SVG\Rasterization\SVGRasterizer
      */
-    public function testShouldRenderBackgroundTransparent()
+    public function testShouldRenderBackgroundTransparent(): void
     {
         $obj = new SVGRasterizer(32, 32, [], 32, 32, null);
         $img = $obj->finish();
@@ -231,7 +231,7 @@ public function testShouldRenderBackgroundTransparent()
     /**
      * @covers \SVG\Rasterization\SVGRasterizer
      */
-    public function testShouldRenderBackgroundSolidWhite()
+    public function testShouldRenderBackgroundSolidWhite(): void
     {
         $obj = new SVGRasterizer(32, 32, [], 32, 32, "#FFFFFF");
         $img = $obj->finish();
@@ -244,7 +244,7 @@ public function testShouldRenderBackgroundSolidWhite()
     /**
      * @covers \SVG\Rasterization\SVGRasterizer
      */
-    public function testShouldRenderBackgroundWhiteSemitransparent()
+    public function testShouldRenderBackgroundWhiteSemitransparent(): void
     {
         $obj = new SVGRasterizer(32, 32, [], 32, 32, "rgba(255,255,255,.5)");
         $img = $obj->finish();
diff --git a/tests/Rasterization/Transform/TransformParserTest.php b/tests/Rasterization/Transform/TransformParserTest.php
index 5d0cb2df..66ba1708 100644
--- a/tests/Rasterization/Transform/TransformParserTest.php
+++ b/tests/Rasterization/Transform/TransformParserTest.php
@@ -12,13 +12,13 @@
  */
 class TransformParserTest extends \PHPUnit\Framework\TestCase
 {
-    private function assertMap(Transform $t, array $expected, array $source)
+    private function assertMap(Transform $t, array $expected, array $source): void
     {
         $t->map($source[0], $source[1]);
         $this->assertEquals($expected, $source);
     }
 
-    public function testParseTransformString()
+    public function testParseTransformString(): void
     {
         $transform = TransformParser::parseTransformString('translate(10,20) scale(3,7) rotate(90)');
         $this->assertMap($transform, [-290, 720], [100, 100]);
diff --git a/tests/Rasterization/Transform/TransformTest.php b/tests/Rasterization/Transform/TransformTest.php
index 3c39c8fd..4cdc1bcd 100644
--- a/tests/Rasterization/Transform/TransformTest.php
+++ b/tests/Rasterization/Transform/TransformTest.php
@@ -11,21 +11,21 @@
  */
 class TransformTest extends \PHPUnit\Framework\TestCase
 {
-    private function assertMap(Transform $t, array $expected, array $source)
+    private function assertMap(Transform $t, array $expected, array $source): void
     {
         $t->map($source[0], $source[1]);
         $this->assertEqualsWithDelta($expected[0], $source[0], 10e-12);
         $this->assertEqualsWithDelta($expected[1], $source[1], 10e-12);
     }
 
-    private function assertResized(Transform $t, array $expected, array $source)
+    private function assertResized(Transform $t, array $expected, array $source): void
     {
         $t->resize($source[0], $source[1]);
         $this->assertEqualsWithDelta($expected[0], $source[0], 10e-12);
         $this->assertEqualsWithDelta($expected[1], $source[1], 10e-12);
     }
 
-    public function testIdentity()
+    public function testIdentity(): void
     {
         $t = Transform::identity();
         $this->assertMap($t, [0, 0], [0, 0]);
@@ -36,7 +36,7 @@ public function testIdentity()
     /**
      * @covers ::resize
      */
-    public function testResize()
+    public function testResize(): void
     {
         $t = Transform::identity();
         $this->assertResized($t, [123, 456], [123, 456]);
@@ -87,7 +87,7 @@ public function testResize()
         $this->assertResized($t, [123 * 3, 456 * 5 * M_SQRT2], [123, 456]);
     }
 
-    public function testMultiply()
+    public function testMultiply(): void
     {
         $t = Transform::identity();
 
@@ -108,7 +108,7 @@ public function testMultiply()
         $this->assertMap($t, [-1411, 2993], [123, 456]);
     }
 
-    public function testTranslate()
+    public function testTranslate(): void
     {
         $t = Transform::identity();
 
@@ -130,7 +130,7 @@ public function testTranslate()
         $this->assertMap($t, [713, 1015], [59, 61]);
     }
 
-    public function testScale()
+    public function testScale(): void
     {
         $t = Transform::identity();
 
@@ -153,7 +153,7 @@ public function testScale()
         $this->assertMap($t, [16882, 24069], [59, 61]);
     }
 
-    public function testRotate()
+    public function testRotate(): void
     {
         $t = Transform::identity();
 
@@ -172,7 +172,7 @@ public function testRotate()
         $this->assertMap($t, [11 + 298 * M_SQRT2, 13 + 417 * M_SQRT2], [59, 61]);
     }
 
-    public function testSkewX()
+    public function testSkewX(): void
     {
         $t = Transform::identity();
 
@@ -192,7 +192,7 @@ public function testSkewX()
         $this->assertMap($t, [312 + 122 * M_SQRT2, 434 + 183 * M_SQRT2], [59, 61]);
     }
 
-    public function testSkewY()
+    public function testSkewY(): void
     {
         $t = Transform::identity();
 
diff --git a/tests/Reading/AttributeRegistryTest.php b/tests/Reading/AttributeRegistryTest.php
index c53aea2a..849c5be6 100644
--- a/tests/Reading/AttributeRegistryTest.php
+++ b/tests/Reading/AttributeRegistryTest.php
@@ -16,7 +16,7 @@ class AttributeRegistryTest extends \PHPUnit\Framework\TestCase
     /**
      * @covers ::isStyle
      */
-    public function testIsStyle()
+    public function testIsStyle(): void
     {
         $this->assertTrue(AttributeRegistry::isStyle('font-size'));
         $this->assertTrue(AttributeRegistry::isStyle('stroke'));
@@ -27,7 +27,7 @@ public function testIsStyle()
     /**
      * @covers ::convertStyleAttribute
      */
-    public function testConvertStyleAttribute()
+    public function testConvertStyleAttribute(): void
     {
         $this->assertSame('42px', AttributeRegistry::convertStyleAttribute('font-size', '42'));
         $this->assertSame('42%', AttributeRegistry::convertStyleAttribute('font-size', '42%'));
diff --git a/tests/Reading/LengthAttributeConverterTest.php b/tests/Reading/LengthAttributeConverterTest.php
index 09d1063b..5ca1eab4 100644
--- a/tests/Reading/LengthAttributeConverterTest.php
+++ b/tests/Reading/LengthAttributeConverterTest.php
@@ -11,7 +11,7 @@
  */
 class LengthAttributeConverterTest extends \PHPUnit\Framework\TestCase
 {
-    public function testShouldQualifyUnitlessNumbers()
+    public function testShouldQualifyUnitlessNumbers(): void
     {
         $obj = LengthAttributeConverter::getInstance();
 
@@ -24,7 +24,7 @@ public function testShouldQualifyUnitlessNumbers()
         $this->assertSame('-42.123px', $obj->convert('-42.123'));
     }
 
-    public function testShouldTrimWhitespace()
+    public function testShouldTrimWhitespace(): void
     {
         $obj = LengthAttributeConverter::getInstance();
 
@@ -33,7 +33,7 @@ public function testShouldTrimWhitespace()
         $this->assertSame('-42.123px', $obj->convert(" \n -42.123 \n "));
     }
 
-    public function testShouldIgnoreOtherValues()
+    public function testShouldIgnoreOtherValues(): void
     {
         $obj = LengthAttributeConverter::getInstance();
 
diff --git a/tests/Reading/NodeRegistryTest.php b/tests/Reading/NodeRegistryTest.php
index 24030ed5..dbc6c2a5 100644
--- a/tests/Reading/NodeRegistryTest.php
+++ b/tests/Reading/NodeRegistryTest.php
@@ -11,15 +11,15 @@
  */
 class NodeRegistryTest extends \PHPUnit\Framework\TestCase
 {
-    public function testShouldConstructKnownTypes()
+    public function testShouldConstructKnownTypes(): void
     {
         $result = NodeRegistry::create('rect');
-        $this->assertInstanceOf('SVG\Nodes\Shapes\SVGRect', $result);
+        $this->assertInstanceOf(\SVG\Nodes\Shapes\SVGRect::class, $result);
     }
 
-    public function testShouldUseGenericTypeForOthers()
+    public function testShouldUseGenericTypeForOthers(): void
     {
         $result = NodeRegistry::create('div');
-        $this->assertInstanceOf('SVG\Nodes\SVGGenericNodeType', $result);
+        $this->assertInstanceOf(\SVG\Nodes\SVGGenericNodeType::class, $result);
     }
 }
diff --git a/tests/Reading/SVGReaderTest.php b/tests/Reading/SVGReaderTest.php
index a9fb7bbc..e5d5b27d 100644
--- a/tests/Reading/SVGReaderTest.php
+++ b/tests/Reading/SVGReaderTest.php
@@ -74,19 +74,19 @@ public function setUp(): void
         $this->xmlEntities .= '</svg>';
     }
 
-    public function testShouldReturnAnImageOrNull()
+    public function testShouldReturnAnImageOrNull(): void
     {
         // should return an instance of SVG
         $svgReader = new SVGReader();
         $result = $svgReader->parseString($this->xml);
-        $this->assertInstanceOf('\SVG\SVG', $result);
+        $this->assertInstanceOf(\SVG\SVG::class, $result);
 
         // should return null when parsing fails
         $result = $svgReader->parseString('<rect />');
         $this->assertNull($result);
     }
 
-    public function testShouldSetAllAttributesAndNamespaces()
+    public function testShouldSetAllAttributesAndNamespaces(): void
     {
         // should retain all document attributes and namespaces
         $svgReader = new SVGReader();
@@ -128,7 +128,7 @@ public function testShouldSetAllAttributesAndNamespaces()
         ], $rect->getSerializableAttributes());
     }
 
-    public function testShouldSetStyles()
+    public function testShouldSetStyles(): void
     {
         $svgReader = new SVGReader();
         $result = $svgReader->parseString($this->xml);
@@ -143,7 +143,7 @@ public function testShouldSetStyles()
         $this->assertEquals('#AABBCC', $rect->getStyle('stroke'));
     }
 
-    public function testShouldConvertUnitlessCSSLengths()
+    public function testShouldConvertUnitlessCSSLengths(): void
     {
         $code  = '<svg xmlns="http://www.w3.org/2000/svg">';
         $code .= '<text font-size="11" letter-spacing="2" word-spacing="3">foo</text>';
@@ -159,7 +159,7 @@ public function testShouldConvertUnitlessCSSLengths()
         $this->assertSame('3px', $text->getStyle('word-spacing'));
     }
 
-    public function testShouldRecursivelyAddChildren()
+    public function testShouldRecursivelyAddChildren(): void
     {
         // should recursively add all child nodes
         $svgReader = new SVGReader();
@@ -184,7 +184,7 @@ public function testShouldRecursivelyAddChildren()
         ], $ellipse->getSerializableAttributes());
     }
 
-    public function testShouldWorkWithoutAnyXmlns()
+    public function testShouldWorkWithoutAnyXmlns(): void
     {
         $svgReader = new SVGReader();
         $result = $svgReader->parseString($this->xmlNoXmlns);
@@ -195,7 +195,7 @@ public function testShouldWorkWithoutAnyXmlns()
         $this->assertSame('10', $doc->getChild(0)->getAttribute('cx'));
     }
 
-    public function testShouldWorkWithoutMainXmlns()
+    public function testShouldWorkWithoutMainXmlns(): void
     {
         $svgReader = new SVGReader();
         $result = $svgReader->parseString($this->xmlOnlyOtherXmlns);
@@ -207,7 +207,7 @@ public function testShouldWorkWithoutMainXmlns()
         $this->assertSame('bar', $doc->getChild(0)->getAttribute('xlink:foo'));
     }
 
-    public function testShouldRetrieveUnknownNodes()
+    public function testShouldRetrieveUnknownNodes(): void
     {
         $svgReader = new SVGReader();
         $result = $svgReader->parseString($this->xmlUnknown);
@@ -227,7 +227,7 @@ public function testShouldRetrieveUnknownNodes()
         $this->assertSame('baz', $doc->getChild(1)->getChild(0)->getName());
     }
 
-    public function testShouldSetValue()
+    public function testShouldSetValue(): void
     {
         $svgReader = new SVGReader();
         $result = $svgReader->parseString($this->xmlValue);
@@ -237,7 +237,7 @@ public function testShouldSetValue()
         $this->assertSame('hello world', $doc->getChild(0)->getValue());
     }
 
-    public function testShouldDecodeEntities()
+    public function testShouldDecodeEntities(): void
     {
         $svgReader = new SVGReader();
         $result = $svgReader->parseString($this->xmlEntities);
@@ -254,7 +254,7 @@ public function testShouldDecodeEntities()
         $this->assertSame('" foo&bar>', $doc->getChild(1)->getValue());
     }
 
-    public function testShouldRemoveCDataForStyles()
+    public function testShouldRemoveCDataForStyles(): void
     {
         // should remove CDATA
         $code  = '<svg xmlns="http://www.w3.org/2000/svg">';
@@ -266,7 +266,7 @@ public function testShouldRemoveCDataForStyles()
         $this->assertSame('g {display:none;}', $doc->getChild(0)->getValue());
     }
 
-    public function testChildKeepsNamespaces()
+    public function testChildKeepsNamespaces(): void
     {
         $code  = '<svg xmlns="http://www.w3.org/2000/svg">';
         $code .= '<foreignObject width="500" height="500" x="20" y="20">';
@@ -282,7 +282,7 @@ public function testChildKeepsNamespaces()
         $this->assertStringContainsString('<div xmlns="http://www.w3.org/1999/xhtml" xmlns:foo="bar">', '' . $result);
     }
 
-    public function testParsesChildNamespacedAttributes()
+    public function testParsesChildNamespacedAttributes(): void
     {
         $code  = '<svg xmlns="http://www.w3.org/2000/svg">';
         $code .= '<foreignObject width="500" height="500" x="20" y="20">';
@@ -298,7 +298,7 @@ public function testParsesChildNamespacedAttributes()
         $this->assertStringContainsString('<p foo:xxx="yyy">', '' . $result);
     }
 
-    public function testShouldRetrieveNamespacedNodes()
+    public function testShouldRetrieveNamespacedNodes(): void
     {
         $code  = '<?xml version="1.0" encoding="utf-8"?>';
         $code .= '<svg xmlns="http://www.w3.org/2000/svg">';
diff --git a/tests/SVGTest.php b/tests/SVGTest.php
index c62c41e1..a75b8cc9 100644
--- a/tests/SVGTest.php
+++ b/tests/SVGTest.php
@@ -32,7 +32,7 @@ public function setUp(): void
     /**
      * @covers ::__construct
      */
-    public function testConstructSetsDocumentDimensions()
+    public function testConstructSetsDocumentDimensions(): void
     {
         $image = new SVG();
         $doc = $image->getDocument();
@@ -48,13 +48,13 @@ public function testConstructSetsDocumentDimensions()
     /**
      * @covers ::getDocument
      */
-    public function testGetDocument()
+    public function testGetDocument(): void
     {
         $image = new SVG();
         $doc = $image->getDocument();
 
         // should be instanceof the correct class
-        $docFragClass = '\SVG\Nodes\Structures\SVGDocumentFragment';
+        $docFragClass = \SVG\Nodes\Structures\SVGDocumentFragment::class;
         $this->assertInstanceOf($docFragClass, $doc);
 
         // should be set to root
@@ -65,7 +65,7 @@ public function testGetDocument()
      * @requires extension gd
      * @covers ::toRasterImage
      */
-    public function testToRasterImage()
+    public function testToRasterImage(): void
     {
         $image = new SVG(37, 42);
         $rasterImage = $image->toRasterImage(100, 200);
@@ -87,7 +87,7 @@ public function testToRasterImage()
     /**
      * @covers ::__toString
      */
-    public function test__toString()
+    public function test__toString(): void
     {
         $image = new SVG(37, 42);
 
@@ -98,7 +98,7 @@ public function test__toString()
     /**
      * @covers ::toXMLString
      */
-    public function testToXMLString()
+    public function testToXMLString(): void
     {
         $image = new SVG(37, 42);
 
@@ -112,13 +112,13 @@ public function testToXMLString()
     /**
      * @covers ::fromString
      */
-    public function testFromString()
+    public function testFromString(): void
     {
         $image = SVG::fromString($this->xml);
         $doc = $image->getDocument();
 
         // should return an instance of SVG
-        $this->assertInstanceOf('\SVG\SVG', $image);
+        $this->assertInstanceOf(\SVG\SVG::class, $image);
 
         // should have correct width and height
         $this->assertSame('37', $doc->getWidth());
@@ -127,7 +127,7 @@ public function testFromString()
         // should succeed without xml declaration
         $image = SVG::fromString($this->xmlNoDeclaration);
         $doc = $image->getDocument();
-        $this->assertInstanceOf('\SVG\SVG', $image);
+        $this->assertInstanceOf(\SVG\SVG::class, $image);
         $this->assertSame('37', $doc->getWidth());
         $this->assertSame('42', $doc->getHeight());
     }
@@ -135,10 +135,10 @@ public function testFromString()
     /**
      * @covers ::fromFile
      */
-    public function testFromFile()
+    public function testFromFile(): void
     {
         $image = SVG::fromFile(__DIR__ . '/php_test.svg');
 
-        $this->assertInstanceOf('\SVG\SVG', $image);
+        $this->assertInstanceOf(\SVG\SVG::class, $image);
     }
 }
diff --git a/tests/Shims/StrTest.php b/tests/Shims/StrTest.php
index d413677f..92398cc2 100644
--- a/tests/Shims/StrTest.php
+++ b/tests/Shims/StrTest.php
@@ -7,7 +7,7 @@
 class StrTest extends TestCase
 {
     /** @dataProvider provideTrimsWithDefaultCharacters */
-    public function testTrimsWithDefaultCharacters($input, $expectedResult)
+    public function testTrimsWithDefaultCharacters($input, $expectedResult): void
     {
         $result = Str::trim($input);
         $this->assertSame($expectedResult, $result);
@@ -31,7 +31,7 @@ public function provideTrimsWithDefaultCharacters()
     }
 
     /** @dataProvider provideTrimsWithCustomCharacters */
-    public function testTrimsWithCustomCharacters($input, $expectedResult)
+    public function testTrimsWithCustomCharacters($input, $expectedResult): void
     {
         $result = Str::trim($input, "NeverGonnaGiveYouUp");
         $this->assertSame($expectedResult, $result);
diff --git a/tests/Utilities/Colors/ColorLookupTest.php b/tests/Utilities/Colors/ColorLookupTest.php
index 499cf282..6dedeca6 100644
--- a/tests/Utilities/Colors/ColorLookupTest.php
+++ b/tests/Utilities/Colors/ColorLookupTest.php
@@ -11,7 +11,7 @@
  */
 class ColorLookupTest extends \PHPUnit\Framework\TestCase
 {
-    public function testGet()
+    public function testGet(): void
     {
         // named colors
         $this->assertEquals([0, 0, 0, 255], ColorLookup::get('black'));
diff --git a/tests/Utilities/Colors/ColorTest.php b/tests/Utilities/Colors/ColorTest.php
index 91fbe144..87eb1541 100644
--- a/tests/Utilities/Colors/ColorTest.php
+++ b/tests/Utilities/Colors/ColorTest.php
@@ -11,7 +11,7 @@
  */
 class ColorTest extends \PHPUnit\Framework\TestCase
 {
-    public function testParse()
+    public function testParse(): void
     {
         // named colors
         $this->assertEquals([0, 0, 0, 255], Color::parse('black'));
diff --git a/tests/Utilities/SVGStyleParserTest.php b/tests/Utilities/SVGStyleParserTest.php
index e396fd90..5034a29a 100644
--- a/tests/Utilities/SVGStyleParserTest.php
+++ b/tests/Utilities/SVGStyleParserTest.php
@@ -11,26 +11,26 @@
  */
 class SVGStyleParserTest extends \PHPUnit\Framework\TestCase
 {
-    public function testParseStylesWithEmptyString()
+    public function testParseStylesWithEmptyString(): void
     {
         $this->assertCount(0, SVGStyleParser::parseStyles(''));
     }
 
-    public function testParseCssWithMatchedElement()
+    public function testParseCssWithMatchedElement(): void
     {
         $result = SVGStyleParser::parseCss('svg {background-color: beige;}');
 
         $this->assertSame('beige', $result['svg']['background-color']);
     }
 
-    public function testParseCssWithSkippedElement()
+    public function testParseCssWithSkippedElement(): void
     {
         $result = SVGStyleParser::parseCss('@font-face {font-family: "Bitstream Vera Serif Bold";}');
 
         $this->assertCount(0, $result);
     }
 
-    public function testParseDuplicateSelectors()
+    public function testParseDuplicateSelectors(): void
     {
         $result = SVGStyleParser::parseCss('svg {background-color: beige;}; svg {stroke: none;} svg { fill: blue }');
 
diff --git a/tests/Utilities/Units/AngleTest.php b/tests/Utilities/Units/AngleTest.php
index d9991f9d..fdd202a0 100644
--- a/tests/Utilities/Units/AngleTest.php
+++ b/tests/Utilities/Units/AngleTest.php
@@ -11,7 +11,7 @@
  */
 class AngleTest extends \PHPUnit\Framework\TestCase
 {
-    public function testConvert()
+    public function testConvert(): void
     {
         // degrees
         $this->assertEquals(15.5, Angle::convert('15.5deg'));
diff --git a/tests/Utilities/Units/LengthTest.php b/tests/Utilities/Units/LengthTest.php
index f21f7bea..475fbeea 100644
--- a/tests/Utilities/Units/LengthTest.php
+++ b/tests/Utilities/Units/LengthTest.php
@@ -11,7 +11,7 @@
  */
 class LengthTest extends \PHPUnit\Framework\TestCase
 {
-    public function testConvert()
+    public function testConvert(): void
     {
         // units
         $this->assertEquals(16, Length::convert('12pt', 100));
diff --git a/tests/Writing/SVGWriterTest.php b/tests/Writing/SVGWriterTest.php
index 8e53d8bb..d97e9985 100644
--- a/tests/Writing/SVGWriterTest.php
+++ b/tests/Writing/SVGWriterTest.php
@@ -13,21 +13,21 @@ class SVGWriterTest extends \PHPUnit\Framework\TestCase
 {
     private $xmlDeclaration = '<?xml version="1.0" encoding="utf-8"?>';
 
-    public function testShouldIncludeXMLDeclaration()
+    public function testShouldIncludeXMLDeclaration(): void
     {
         // should start with the XML declaration
         $obj = new SVGWriter();
         $this->assertEquals($this->xmlDeclaration, $obj->getString());
     }
 
-    public function testShouldSupportStandaloneFalse()
+    public function testShouldSupportStandaloneFalse(): void
     {
         // should not prepend the XML declaration
         $obj = new SVGWriter(false);
         $this->assertEquals('', $obj->getString());
     }
 
-    public function testShouldWriteTags()
+    public function testShouldWriteTags(): void
     {
         // should write opening and closing tags for containers
         $obj = new SVGWriter();
@@ -44,7 +44,7 @@ public function testShouldWriteTags()
         $this->assertEquals($expect, $obj->getString());
     }
 
-    public function testShouldWriteAttributes()
+    public function testShouldWriteAttributes(): void
     {
         // should write attributes for containers
         $obj = new SVGWriter();
@@ -55,7 +55,7 @@ public function testShouldWriteAttributes()
         $this->assertEquals($expect, $obj->getString());
     }
 
-    public function testShouldWriteStyles()
+    public function testShouldWriteStyles(): void
     {
         // should serialize styles correctly
         $obj = new SVGWriter();
@@ -66,7 +66,7 @@ public function testShouldWriteStyles()
         $this->assertEquals($expect, $obj->getString());
     }
 
-    public function testShouldWriteChildren()
+    public function testShouldWriteChildren(): void
     {
         // should write children
         $obj = new SVGWriter();
@@ -81,7 +81,7 @@ public function testShouldWriteChildren()
         $this->assertEquals($expect, $obj->getString());
     }
 
-    public function testShouldWriteStyleTagInCDATA()
+    public function testShouldWriteStyleTagInCDATA(): void
     {
         // should enclose style tag content in <![CDATA[...]]>
         $obj = new SVGWriter();
@@ -92,7 +92,7 @@ public function testShouldWriteStyleTagInCDATA()
         $this->assertEquals($expect, $obj->getString());
     }
 
-    public function testShouldEncodeEntities()
+    public function testShouldEncodeEntities(): void
     {
         // should encode entities in attributes
         $obj = new SVGWriter();
@@ -119,7 +119,7 @@ public function testShouldEncodeEntities()
         $this->assertEquals($expect, $obj->getString());
     }
 
-    public function testShouldWriteValue()
+    public function testShouldWriteValue(): void
     {
         // should add value before closing tag
         $obj = new SVGWriter();