Shadow: add unit tests for shadow support

backport-changelog/6279.md

@@ -0,0 +1,3 @@
+https://github.com/WordPress/wordpress-develop/pull/6279
+
+* https://github.com/WordPress/gutenberg/pull/60063

phpunit/block-supports/shadow-test.php

@@ -0,0 +1,112 @@
+<?php
+
+/**
+ * Test the shadow block supports.
+ *
+ * @package Gutenberg
+ */
+
+class WP_Block_Supports_Shadow_Test extends WP_UnitTestCase {
+	/**
+	 * @var string|null
+	 */
+	private $test_block_name;
+
+	public function set_up() {
+		parent::set_up();
+		$this->test_block_name = null;
+	}
+
+	public function tear_down() {
+		unregister_block_type( $this->test_block_name );
+		$this->test_block_name = null;
+		parent::tear_down();
+	}
+
+	/**
+	 * Registers a new block for testing shadow support.
+	 *
+	 * @param string $block_name Name for the test block.
+	 * @param array  $supports   Array defining block support configuration.
+	 *
+	 * @return WP_Block_Type The block type for the newly registered test block.
+	 */
+	private function register_shadow_block_with_support( $block_name, $supports = array() ) {
+		$this->test_block_name = $block_name;
+		register_block_type(
+			$this->test_block_name,
+			array(
+				'api_version' => 3,
+				'attributes'  => array(
+					'style' => array(
+						'type' => 'object',
+					),
+				),
+				'supports'    => $supports,
+			)
+		);
+		$registry = WP_Block_Type_Registry::get_instance();
+
+		return $registry->get_registered( $this->test_block_name );
+	}
+
+	/**
+	 * Tests the generation of shadow block support styles.
+	 *
+	 * @dataProvider data_generate_shadow_fixtures
+	 *
+	 * @param boolean|array $support Shadow block support configuration.
+	 * @param string        $value   Shadow style value for style attribute object.
+	 * @param array         $expected       Expected shadow block support styles.
+	 */
+	public function test_gutenberg_apply_shadow_support( $support, $value, $expected ) {
+		$block_type  = self::register_shadow_block_with_support(
+			'test/shadow-block',
+			array( 'shadow' => $support )
+		);
+		$block_attrs = array( 'style' => array( 'shadow' => $value ) );
+		$actual      = gutenberg_apply_shadow_support( $block_type, $block_attrs );
+
+		$this->assertSame( $expected, $actual );
+	}
+
+	/**
+	 * Data provider.
+	 *
+	 * @return array
+	 */
+	public function data_generate_shadow_fixtures() {
+		return array(
+			'with no styles'               => array(
+				'support'  => true,
+				'value'    => '',
+				'expected' => array(),
+			),
+			'without support'              => array(
+				'support'  => false,
+				'value'    => '1px 1px 1px #000',
+				'expected' => array(),
+			),
+			'with single shadow'           => array(
+				'support'  => true,
+				'value'    => '1px 1px 1px #000',
+				'expected' => array( 'style' => 'box-shadow:1px 1px 1px #000;' ),
+			),
+			'with comma separated shadows' => array(
+				'support'  => true,
+				'value'    => '1px 1px 1px #000, 2px 2px 2px #fff',
+				'expected' => array( 'style' => 'box-shadow:1px 1px 1px #000, 2px 2px 2px #fff;' ),
+			),
+			'with preset shadow'           => array(
+				'support'  => true,
+				'value'    => 'var:preset|shadow|natural',
+				'expected' => array( 'style' => 'box-shadow:var(--wp--preset--shadow--natural);' ),
+			),
+			'with serialization skipped'   => array(
+				'support'  => array( '__experimentalSkipSerialization' => true ),
+				'value'    => '1px 1px 1px #000',
+				'expected' => array(),
+			),
+		);
+	}
+}