diff --git a/bin/phpcsDiffFilter b/bin/phpcsDiffFilter
index 8f00341..8bef469 100755
--- a/bin/phpcsDiffFilter
+++ b/bin/phpcsDiffFilter
@@ -1,19 +1,3 @@
 #!/usr/bin/env php
 <?php
-namespace exussum12\CoverageChecker;
-
-include (__DIR__ . "/../functions.php");
-
-findAutoLoader();
-$args = new ArgParser($argv);
-checkCallIsCorrect($args);
-$minimumPercentCovered = getMinPercent($args->getArg(3));
-
-$matcher = new FileMatchers\EndsWith();
-$diff = new  DiffFileLoader($args->getArg(1));
-$phpcs = new PhpCsLoader($args->getArg(2));
-$coverageCheck = new CoverageCheck($diff, $phpcs, $matcher);
-
-$lines = $coverageCheck->getCoveredLines();
-
-handleOutput($lines, $minimumPercentCovered);
+require __DIR__ . '/../src/runners/phpcsDiffFilter.php';
diff --git a/bin/phpmdDiffFilter b/bin/phpmdDiffFilter
index 146753e..4b061fe 100755
--- a/bin/phpmdDiffFilter
+++ b/bin/phpmdDiffFilter
@@ -1,24 +1,3 @@
 #!/usr/bin/env php
 <?php
-namespace exussum12\CoverageChecker;
-
-include (__DIR__ . "/../functions.php");
-
-findAutoLoader();
-$args = new ArgParser($argv);
-checkCallIsCorrect($args);
-$minimumPercentCovered = getMinPercent($args->getArg(3));
-
-$matcher = new FileMatchers\EndsWith();
-
-$diff = new  DiffFileLoader(adjustForStdIn($args->getArg(1)));
-$phpmd = new PhpMdLoader(adjustForStdIn($args->getArg(2)));
-if ($args->getArg("strict")) {
-    $phpmd = new PhpMdLoaderStrict(adjustForStdIn($args->getArg(2)));
-}
-
-$coverageCheck = new CoverageCheck($diff, $phpmd, $matcher);
-
-$lines = $coverageCheck->getCoveredLines();
-
-handleOutput($lines, $minimumPercentCovered);
+require __DIR__ . '/../src/runners/phpmdDiffFilter.php';
diff --git a/bin/phpunitDiffFilter b/bin/phpunitDiffFilter
index 3dd94e0..89752cd 100755
--- a/bin/phpunitDiffFilter
+++ b/bin/phpunitDiffFilter
@@ -1,19 +1,3 @@
 #!/usr/bin/env php
 <?php
-namespace exussum12\CoverageChecker;
-
-require_once (__DIR__ . "/../functions.php");
-
-findAutoLoader();
-$args = new ArgParser($argv);
-checkCallIsCorrect($args);
-$minimumPercentCovered = getMinPercent($args->getArg(3));
-
-$matcher = new FileMatchers\EndsWith();
-$diff = new  DiffFileLoader($args->getArg(1));
-$phpunit = new XMLReport($args->getArg(2));
-$coverageCheck = new CoverageCheck($diff, $phpunit, $matcher);
-
-$lines = $coverageCheck->getCoveredLines();
-
-handleOutput($lines, $minimumPercentCovered);
+require __DIR__ . '/../src/runners/phpunitDiffFilter.php';
diff --git a/phpunit.xml b/phpunit.xml
index 60e4c49..9efa5b8 100644
--- a/phpunit.xml
+++ b/phpunit.xml
@@ -13,7 +13,7 @@
     </testsuite>
 
     <filter>
-        <whitelist processUncoveredFilesFromWhitelist="true">
+        <whitelist addUncoveredFilesFromWhitelist="true">
             <directory suffix=".php">src</directory>
         </whitelist>
     </filter>
diff --git a/src/ArgParser.php b/src/ArgParser.php
index 1ee8696..47afb45 100644
--- a/src/ArgParser.php
+++ b/src/ArgParser.php
@@ -21,7 +21,7 @@ public function getArg($name)
 
     protected function numericArg($position)
     {
-        foreach($this->args as $arg) {
+        foreach ($this->args as $arg) {
             if ($arg{0} != '-' && $position-- == 0) {
                 return $arg;
             }
@@ -35,8 +35,7 @@ protected function letterArg($name)
         $name = strlen($name) == 1 ?
             "-" . $name :
             "--" . $name;
-
-        foreach($this->args as $arg) {
+        foreach ($this->args as $arg) {
             if ($arg{0} == '-' && $name == $arg) {
                 return true;
             }
diff --git a/src/DiffFileLoader.php b/src/DiffFileLoader.php
index 7bf49a8..f66c07d 100644
--- a/src/DiffFileLoader.php
+++ b/src/DiffFileLoader.php
@@ -49,7 +49,7 @@ public function getChangedLines()
     private function getLineHandle($line)
     {
         foreach ($this->diffLines as $lineType) {
-	    $lineType = $this->getClass($lineType);
+            $lineType = $this->getClass($lineType);
             if ($lineType->isValid($line)) {
                 return $lineType;
             }
diff --git a/src/PhpMdLoader.php b/src/PhpMdLoader.php
index ee901fb..4a0262e 100644
--- a/src/PhpMdLoader.php
+++ b/src/PhpMdLoader.php
@@ -48,11 +48,11 @@ public function getLines()
     public function isValidLine($file, $lineNumber)
     {
         $valid = true;
-        foreach($this->errorRanges[$file] as $number => $errors) {
-            if (
+        foreach ($this->errorRanges[$file] as $number => $errors) {
+            if ((
                 $errors['start'] >= $lineNumber &&
                 $errors['end'] <= $lineNumber
-            ) {
+            )) {
                 //unset this error
                 unset($this->errorRanges[$file][$number]);
                 $valid = false;
diff --git a/functions.php b/src/functions.php
similarity index 62%
rename from functions.php
rename to src/functions.php
index 2cf7676..c1a613e 100644
--- a/functions.php
+++ b/src/functions.php
@@ -1,11 +1,13 @@
 <?php
 namespace exussum12\CoverageChecker;
 
+use Exception;
+
 function findAutoLoader()
 {
     $locations = [
-        __DIR__ . '/vendor/autoload.php',
-        __DIR__ . '/autoload.php'
+        __DIR__ . '/../vendor/autoload.php',
+        __DIR__ . '/../autoload.php'
     ];
 
     $found = false;
@@ -17,7 +19,7 @@ function findAutoLoader()
             break;
         }
     }
-
+    // @codeCoverageIgnoreStart
     if (!$found) {
         error_log(
             "Can't find the autoload file," .
@@ -25,19 +27,23 @@ function findAutoLoader()
         );
 
         exit(1);
+    // @codeCoverageIgnoreEnd
     }
 }
 
 function checkCallIsCorrect(ArgParser $args)
 {
-    if (false === $args->getArg(1) || false === $args->getArg(2)) {
-        error_log(
-            "Missing arguments, please call with diff and check file"
+    if (!$args->getArg(1) || !$args->getArg(2)) {
+        throw new Exception(
+            "Missing arguments, please call with diff and check file",
+            1
         );
-        exit(1);
     }
 }
 
+/**
+ * @codeCoverageIgnore
+ */
 function adjustForStdIn($argument)
 {
     if ($argument == "-") {
@@ -63,14 +69,14 @@ function getMinPercent($percent)
 
 function handleOutput($lines, $minimumPercentCovered)
 {
-    $coveredLines = count($lines['coveredLines'], COUNT_RECURSIVE);
-    $uncoveredLines = count($lines['uncoveredLines'], COUNT_RECURSIVE);
+    $coveredLines = calculateLines($lines['coveredLines']);
+    $uncoveredLines = calculateLines($lines['uncoveredLines']);
+
 
     if ($coveredLines + $uncoveredLines == 0) {
         echo "No lines found!";
-        exit(0);
+        return;
     }
-
     $percentCovered = 100 * ($coveredLines / ($coveredLines + $uncoveredLines));
     
     $extra = PHP_EOL;
@@ -85,8 +91,28 @@ function handleOutput($lines, $minimumPercentCovered)
     printf('%.2f%% Covered%s', $percentCovered, $extra);
     
     if ($percentCovered >= $minimumPercentCovered) {
-        exit(0);
+        return;
     }
 
-    exit(2);
+    throw new Exception(
+        "Failing due to coverage being lower than threshold",
+        2
+    );
+}
+
+function calculateLines($lines)
+{
+    return count($lines, COUNT_RECURSIVE) - count($lines);
+}
+
+function addExceptionHandler()
+{
+    set_exception_handler(
+        function (Exception $exception) {
+            // @codeCoverageIgnoreStart
+            error_log($exception->getMessage());
+            exit($exception->getCode());
+            // @codeCoverageIgnoreEnd
+        }
+    );
 }
diff --git a/src/runners/phpcsDiffFilter.php b/src/runners/phpcsDiffFilter.php
new file mode 100644
index 0000000..e74c66f
--- /dev/null
+++ b/src/runners/phpcsDiffFilter.php
@@ -0,0 +1,20 @@
+<?php
+namespace exussum12\CoverageChecker;
+
+require_once __DIR__ . "/../functions.php";
+global $argv;
+
+addExceptionHandler();
+findAutoLoader();
+$args = new ArgParser($argv);
+checkCallIsCorrect($args);
+$minimumPercentCovered = getMinPercent($args->getArg(3));
+
+$matcher = new FileMatchers\EndsWith();
+$diff = new  DiffFileLoader($args->getArg(1));
+$phpcs = new PhpCsLoader($args->getArg(2));
+$coverageCheck = new CoverageCheck($diff, $phpcs, $matcher);
+
+$lines = $coverageCheck->getCoveredLines();
+
+handleOutput($lines, $minimumPercentCovered);
diff --git a/src/runners/phpmdDiffFilter.php b/src/runners/phpmdDiffFilter.php
new file mode 100644
index 0000000..8fe9e62
--- /dev/null
+++ b/src/runners/phpmdDiffFilter.php
@@ -0,0 +1,25 @@
+<?php
+namespace exussum12\CoverageChecker;
+
+require_once __DIR__ . "/../functions.php";
+global $argv;
+
+addExceptionHandler();
+findAutoLoader();
+$args = new ArgParser($argv);
+checkCallIsCorrect($args);
+$minimumPercentCovered = getMinPercent($args->getArg(3));
+
+$matcher = new FileMatchers\EndsWith();
+
+$diff = new  DiffFileLoader(adjustForStdIn($args->getArg(1)));
+$phpmd = new PhpMdLoader(adjustForStdIn($args->getArg(2)));
+if ($args->getArg("strict")) {
+    $phpmd = new PhpMdLoaderStrict(adjustForStdIn($args->getArg(2)));
+}
+
+$coverageCheck = new CoverageCheck($diff, $phpmd, $matcher);
+
+$lines = $coverageCheck->getCoveredLines();
+
+handleOutput($lines, $minimumPercentCovered);
diff --git a/src/runners/phpunitDiffFilter.php b/src/runners/phpunitDiffFilter.php
new file mode 100644
index 0000000..1ed0012
--- /dev/null
+++ b/src/runners/phpunitDiffFilter.php
@@ -0,0 +1,20 @@
+<?php
+namespace exussum12\CoverageChecker;
+
+global $argv;
+
+require_once __DIR__ . "/../functions.php";
+addExceptionHandler();
+findAutoLoader();
+$args = new ArgParser($argv);
+checkCallIsCorrect($args);
+$minimumPercentCovered = getMinPercent($args->getArg(3));
+
+$matcher = new FileMatchers\EndsWith();
+$diff = new  DiffFileLoader($args->getArg(1));
+$phpunit = new XMLReport($args->getArg(2));
+$coverageCheck = new CoverageCheck($diff, $phpunit, $matcher);
+
+$lines = $coverageCheck->getCoveredLines();
+
+handleOutput($lines, $minimumPercentCovered);
diff --git a/tests/DiffFileLoadTest.php b/tests/DiffFileLoadTest.php
index 8ceabad..971b8e4 100644
--- a/tests/DiffFileLoadTest.php
+++ b/tests/DiffFileLoadTest.php
@@ -22,7 +22,7 @@ public function testDiffResultsMatch($file, $expected)
      */
     public function testNonExistantFile()
     {
-        $changed = $this->getChangedLines('ufhbubfusdf');
+        $this->getChangedLines('ufhbubfusdf');
     }
 
     public function getResults()
diff --git a/tests/LoadPhpcsReportTest.php b/tests/LoadPhpcsReportTest.php
index 3a51760..62c9b23 100644
--- a/tests/LoadPhpcsReportTest.php
+++ b/tests/LoadPhpcsReportTest.php
@@ -27,7 +27,7 @@ public function testCanMakeClass()
      */
     public function testRejectsInvalidData()
     {
-        $phpcs = new PhpCsLoader(__DIR__ . '/fixtures/change.txt');
+        new PhpCsLoader(__DIR__ . '/fixtures/change.txt');
     }
 
     public function testCorrectMissingFile()
diff --git a/tests/PhpcsDiffFilterTest.php b/tests/PhpcsDiffFilterTest.php
new file mode 100644
index 0000000..2415511
--- /dev/null
+++ b/tests/PhpcsDiffFilterTest.php
@@ -0,0 +1,21 @@
+<?php
+namespace exussum12\CoverageChecker\tests;
+
+use PHPUnit\Framework\TestCase;
+
+class PhpcsDiffFilterTest extends TestCase
+{
+
+    public function testValid()
+    {
+        $GLOBALS['argv'] = [
+            'phpunitDiffFilter',
+            __DIR__ . '/fixtures/change.txt',
+            __DIR__ . '/fixtures/phpcs.json'
+        ];
+        ob_start();
+        require(__DIR__ . "/../src/runners/phpcsDiffFilter.php");
+        $output = ob_get_clean();
+        $this->assertContains('100.00%', $output);
+    }
+}
diff --git a/tests/PhpmdDiffFilterTest.php b/tests/PhpmdDiffFilterTest.php
new file mode 100644
index 0000000..3013141
--- /dev/null
+++ b/tests/PhpmdDiffFilterTest.php
@@ -0,0 +1,63 @@
+<?php
+namespace exussum12\CoverageChecker\tests;
+
+use PHPUnit\Framework\TestCase;
+use Exception;
+
+class PhpmdDiffFilterTest extends TestCase
+{
+
+    public function testValid()
+    {
+        $GLOBALS['argv'] = [
+            'phpunitDiffFilter',
+            __DIR__ . '/fixtures/change.txt',
+            __DIR__ . '/fixtures/phpmd.xml'
+        ];
+        ob_start();
+        require(__DIR__ . "/../src/runners/phpmdDiffFilter.php");
+        $output = ob_get_clean();
+        $this->assertContains('100.00%', $output);
+    }
+
+    public function testNoValidLines()
+    {
+        $GLOBALS['argv'] = [
+            'phpunitDiffFilter',
+            __DIR__ . '/fixtures/change.txt',
+            __DIR__ . '/fixtures/phpmd-change.xml',
+        ];
+        try {
+            ob_start();
+            require(__DIR__ . "/../src/runners/phpmdDiffFilter.php");
+        } catch (Exception $e) {
+            $output = ob_get_clean();
+            $this->assertEquals(2, $e->getCode());
+            $this->assertContains('0.00%', $output);
+            return;
+        }
+        $this->fail("no exception thrown");
+
+    }
+
+    public function testNoValidLinesStrict()
+    {
+        $GLOBALS['argv'] = [
+            'phpunitDiffFilter',
+            __DIR__ . '/fixtures/change.txt',
+            __DIR__ . '/fixtures/phpmd-change.xml',
+            '--strict',
+        ];
+        try {
+            ob_start();
+            require(__DIR__ . "/../src/runners/phpmdDiffFilter.php");
+        } catch (Exception $e) {
+            $output = ob_get_clean();
+            $this->assertEquals(2, $e->getCode());
+            $this->assertContains('0%', $output);
+            return;
+        }
+
+        $this->fail("no exception thrown");
+    }
+}
diff --git a/tests/PhpunitDiffFilterTest.php b/tests/PhpunitDiffFilterTest.php
new file mode 100644
index 0000000..d584301
--- /dev/null
+++ b/tests/PhpunitDiffFilterTest.php
@@ -0,0 +1,81 @@
+<?php
+namespace exussum12\CoverageChecker\tests;
+
+use PHPUnit\Framework\TestCase;
+use Exception;
+
+class PhpunitDiffFilterTest extends TestCase
+{
+    /**
+     * @expectedException Exception
+     * @expectedExceptionCode 1
+     */
+    public function testWrongArgs()
+    {
+        $GLOBALS['argv'] = [];
+        require(__DIR__ . "/../src/runners/phpunitDiffFilter.php");
+    }
+
+    public function testWorkingCorrectly()
+    {
+        $GLOBALS['argv'] = [
+            'phpunitDiffFilter',
+            __DIR__ . '/fixtures/change.txt',
+            __DIR__ . '/fixtures/coverage.xml'
+        ];
+        ob_start();
+        require(__DIR__ . "/../src/runners/phpunitDiffFilter.php");
+        $output = ob_get_clean();
+        $this->assertContains('100.00%', $output);
+    }
+
+    public function testFailingBuild()
+    {
+        $GLOBALS['argv'] = [
+            'phpunitDiffFilter',
+            __DIR__ . '/fixtures/newFile.txt',
+            __DIR__ . '/fixtures/coverage-change.xml',
+            70
+        ];
+        try {
+            ob_start();
+            require(__DIR__ . "/../src/runners/phpunitDiffFilter.php");
+        } catch (Exception $e) {
+            $output = ob_get_clean();
+            $this->assertEquals(2, $e->getCode());
+            $this->assertContains('66.67%', $output);
+            return;
+        }
+
+        $this->fail("no exception thrown");
+    }
+
+    public function testPassingLowPercentage()
+    {
+        $GLOBALS['argv'] = [
+            'phpunitDiffFilter',
+            __DIR__ . '/fixtures/newFile.txt',
+            __DIR__ . '/fixtures/coverage-change.xml',
+            60
+        ];
+
+        ob_start();
+        require(__DIR__ . "/../src/runners/phpunitDiffFilter.php");
+        $output = ob_get_clean();
+        $this->assertContains('66.67%', $output);
+    }
+
+    public function testNoCoveredLines()
+    {
+        $GLOBALS['argv'] = [
+            'phpunitDiffFilter',
+            __DIR__ . '/fixtures/removeFile.txt',
+            __DIR__ . '/fixtures/coverage-change.xml',
+        ];
+
+        ob_start();
+        require(__DIR__ . "/../src/runners/phpunitDiffFilter.php");
+        $output = ob_get_clean();
+        $this->assertContains('No lines found', $output);
+    }
+}
diff --git a/tests/fixtures/coverage-change.xml b/tests/fixtures/coverage-change.xml
new file mode 100644
index 0000000..f5ee4ed
--- /dev/null
+++ b/tests/fixtures/coverage-change.xml
@@ -0,0 +1,29 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<coverage generated="123456">
+  <project timestamp="123456">
+    <package name="ns\packageName">
+      <file name="/path/to/file/changedFile.php">
+        <line num="3" type="stmt" count="0"/>
+        <line num="10" type="stmt" count="4"/>
+        <line num="11" type="stmt" count="4"/>
+        <line num="14" type="stmt" count="0"/>
+        <line num="15" type="stmt" count="3"/>
+        <line num="17" type="method" name="randomMethod" visibility="public" complexity="2" crap="2" count="3"/>
+        <line num="18" type="stmt" count="3"/>
+        <line num="19" type="stmt" count="3"/>
+        <line num="22" type="stmt" count="3"/>
+        <metrics loc="25" ncloc="25" classes="0" methods="2" coveredmethods="2" conditionals="0" coveredconditionals="0" statements="13" coveredstatements="13" elements="19" coveredelements="19"/>
+      </file>
+      <file name="/path/to/file/otherFile.php">
+        <class name="diffLineHandle" namespace="ns\packageName">
+          <metrics complexity="3" methods="1" coveredmethods="1" conditionals="0" coveredconditionals="0" statements="2" coveredstatements="2" elements="3" coveredelements="3"/>
+        </class>
+        <line num="7" type="method" name="__construct" visibility="public" complexity="1" crap="1" count="4"/>
+        <line num="9" type="stmt" count="4"/>
+        <line num="10" type="stmt" count="4"/>
+        <metrics loc="25" ncloc="25" classes="0" methods="2" coveredmethods="2" conditionals="0" coveredconditionals="0" statements="13" coveredstatements="13" elements="19" coveredelements="19"/>
+      </file>
+    </package>
+    <metrics loc="15" ncloc="15" classes="1" methods="1" coveredmethods="1" conditionals="0" coveredconditionals="0" statements="2" coveredstatements="2" elements="3" coveredelements="3"/>
+  </project>
+</coverage>
diff --git a/tests/fixtures/phpmd-change.xml b/tests/fixtures/phpmd-change.xml
new file mode 100644
index 0000000..1810c31
--- /dev/null
+++ b/tests/fixtures/phpmd-change.xml
@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8" ?>
+<pmd version="@project.version@" timestamp="2017-01-04T18:31:17+00:00">
+  <file name="/full/path/to/file/src/changedFile.php">
+    <violation beginline="3" endline="3" rule="BooleanArgumentFlag" ruleset="Clean Code Rules" externalInfoUrl="http://phpmd.org/rules/cleancode.html#booleanargumentflag" priority="1">
+      The method addUnCoveredLine has a boolean flag argument $message, which is a certain sign of a Single Responsibility Principle violation.
+    </violation>
+  </file>
+</pmd>