diff --git a/plugins/dominant-color-images/load.php b/plugins/dominant-color-images/load.php
index 41672f9b5d..223204885d 100644
--- a/plugins/dominant-color-images/load.php
+++ b/plugins/dominant-color-images/load.php
@@ -19,7 +19,7 @@
 if ( ! defined( 'ABSPATH' ) ) {
 	exit; // Exit if accessed directly.
 }
-// @codeCoverageIgnoreEnd
+
 
 // Define required constants.
 if ( defined( 'DOMINANT_COLOR_IMAGES_VERSION' ) ) {
@@ -30,3 +30,4 @@
 
 require_once __DIR__ . '/helper.php';
 require_once __DIR__ . '/hooks.php';
+// @codeCoverageIgnoreEnd
diff --git a/plugins/dominant-color-images/tests/test-dominant-color-image-editor-imagick.php b/plugins/dominant-color-images/tests/test-dominant-color-image-editor-imagick.php
index 5dde0bae6a..4f9a66b326 100644
--- a/plugins/dominant-color-images/tests/test-dominant-color-image-editor-imagick.php
+++ b/plugins/dominant-color-images/tests/test-dominant-color-image-editor-imagick.php
@@ -8,7 +8,12 @@
  */
 
 use Dominant_Color_Images\Tests\TestCase;
+use Imagick;
+use ImagickPixel;
 
+/**
+ * @coversDefaultClass Dominant_Color_Image_Editor_Imagick
+ */
 class Test_Dominant_Color_Image_Editor_Imagick extends TestCase {
 
 	/**
@@ -33,4 +38,164 @@ static function ( $editor ): bool {
 			}
 		);
 	}
+
+	/**
+	 * @covers ::get_dominant_color
+	 */
+	public function test_failure_handling(): void {
+		$editor = new Dominant_Color_Image_Editor_Imagick( '/image.jpg' );
+		$result = $editor->get_dominant_color();
+		$this->assertWPError( $result );
+		$this->assertEquals( 'image_editor_dominant_color_error_no_image', $result->get_error_code() );
+	}
+
+	/**
+	 * @covers ::get_dominant_color
+	 */
+	public function test_get_dominant_color_no_image(): void {
+		$editor = new Dominant_Color_Image_Editor_Imagick( null );
+		$result = $editor->get_dominant_color();
+
+		$this->assertWPError( $result );
+		$this->assertEquals( 'image_editor_dominant_color_error_no_image', $result->get_error_code() );
+	}
+
+	/**
+	 * @covers ::get_dominant_color
+	 */
+	public function test_get_dominant_color_exception(): void {
+		// Creating mock that will throw an exception.
+		$mock = $this->getMockBuilder( Dominant_Color_Image_Editor_Imagick::class )
+					->onlyMethods( array( '__construct' ) )
+					->disableOriginalConstructor()
+					->getMock();
+
+		$reflection = new ReflectionClass( $mock );
+		$property   = $reflection->getProperty( 'image' );
+		$property->setAccessible( true );
+		$property->setValue( $mock, new Imagick() );
+
+		$result = $mock->get_dominant_color();
+
+		$this->assertWPError( $result );
+		$this->assertEquals( 'image_editor_dominant_color_error', $result->get_error_code() );
+	}
+
+	/**
+	 * @covers ::has_transparency
+	 */
+	public function test_has_transparency_no_image(): void {
+		$editor = new Dominant_Color_Image_Editor_Imagick( null );
+		$result = $editor->has_transparency();
+
+		$this->assertWPError( $result );
+		$this->assertEquals( 'image_editor_has_transparency_error_no_image', $result->get_error_code() );
+	}
+
+	/**
+	 * @covers ::has_transparency
+	 */
+	public function test_has_no_transparency(): void {
+		$imagick = new Imagick();
+		$imagick->newImage( 1, 1, new ImagickPixel( 'red' ) );
+
+		$editor     = new Dominant_Color_Image_Editor_Imagick( null );
+		$reflection = new ReflectionClass( $editor );
+		$property   = $reflection->getProperty( 'image' );
+		$property->setAccessible( true );
+		$property->setValue( $editor, $imagick );
+
+		$result = $editor->has_transparency();
+
+		$this->assertFalse( $result );
+	}
+
+	/**
+	 * @covers ::has_transparency
+	 */
+	public function test_has_transparency_exception(): void {
+		// Creating mock that will throw an exception.
+		$mock = $this->getMockBuilder( Dominant_Color_Image_Editor_Imagick::class )
+					->onlyMethods( array( '__construct' ) )
+					->disableOriginalConstructor()
+					->getMock();
+
+		$reflection = new ReflectionClass( $mock );
+		$property   = $reflection->getProperty( 'image' );
+		$property->setAccessible( true );
+		$property->setValue( $mock, new Imagick() );
+
+		$result = $mock->has_transparency();
+
+		$this->assertWPError( $result );
+		$this->assertEquals( 'image_editor_has_transparency_error', $result->get_error_code() );
+	}
+
+	/**
+	 * @covers ::get_dominant_color
+	 */
+	public function test_get_dominant_color_success(): void {
+		// Create a red test image.
+		$imagick = new Imagick();
+		$imagick->newImage( 1, 1, new ImagickPixel( '#FF0000' ) );
+
+		$editor     = new Dominant_Color_Image_Editor_Imagick( null );
+		$reflection = new ReflectionClass( $editor );
+		$property   = $reflection->getProperty( 'image' );
+		$property->setAccessible( true );
+		$property->setValue( $editor, $imagick );
+
+		$result = $editor->get_dominant_color();
+
+		$this->assertEquals( 'ff0000', $result );
+	}
+
+	/**
+	 * @covers ::has_transparency
+	 */
+	public function test_has_transparency_with_transparency(): void {
+		// Create an image with transparency.
+		$imagick = new Imagick();
+		$imagick->newImage( 1, 1, new ImagickPixel( 'rgba(255,0,0,0.5)' ) );
+
+		$editor     = new Dominant_Color_Image_Editor_Imagick( null );
+		$reflection = new ReflectionClass( $editor );
+		$property   = $reflection->getProperty( 'image' );
+		$property->setAccessible( true );
+		$property->setValue( $editor, $imagick );
+
+		$result = $editor->has_transparency();
+
+		$this->assertTrue( $result );
+	}
+
+	/**
+	 * @covers ::has_transparency
+	 */
+	public function test_has_transparency_no_alpha_channel_method(): void {
+		// Mock the Imagick object to simulate when getImageAlphaChannel method doesn't exist.
+		$imagick_mock = $this->getMockBuilder( Imagick::class )
+							->disableOriginalConstructor()
+							->getMock();
+
+		$imagick_mock->method( 'getImageWidth' )->willReturn( 1 );
+		$imagick_mock->method( 'getImageHeight' )->willReturn( 1 );
+
+		$pixel = $this->getMockBuilder( ImagickPixel::class )
+						->disableOriginalConstructor()
+						->getMock();
+		$pixel->method( 'getColor' )->willReturn( array( 'a' => 0 ) );
+
+		$imagick_mock->method( 'getImagePixelColor' )->willReturn( $pixel );
+
+		$editor     = new Dominant_Color_Image_Editor_Imagick( null );
+		$reflection = new ReflectionClass( $editor );
+		$property   = $reflection->getProperty( 'image' );
+		$property->setAccessible( true );
+		$property->setValue( $editor, $imagick_mock );
+
+		$result = $editor->has_transparency();
+
+		$this->assertFalse( $result );
+	}
 }
diff --git a/plugins/dominant-color-images/tests/test-dominant-color.php b/plugins/dominant-color-images/tests/test-dominant-color.php
index 9c321c9c8e..f899b58595 100644
--- a/plugins/dominant-color-images/tests/test-dominant-color.php
+++ b/plugins/dominant-color-images/tests/test-dominant-color.php
@@ -42,7 +42,7 @@ public function test_dominant_color_metadata( string $image_path, array $expecte
 	 *
 	 * @dataProvider provider_get_dominant_color
 	 *
-	 * @covers ::dominant_color_get_dominant_color
+	 * @covers helper::dominant_color_get_dominant_color
 	 *
 	 * @param string   $image_path Image path.
 	 * @param string[] $expected_color Expected color.
@@ -91,7 +91,7 @@ public function test_has_transparency_metadata( string $image_path, array $expec
 	 *
 	 * @dataProvider provider_get_dominant_color
 	 *
-	 * @covers ::dominant_color_get_dominant_color
+	 * @covers helper::dominant_color_get_dominant_color
 	 *
 	 * @param string   $image_path Image path.
 	 * @param string[] $expected_color Expected color.
@@ -113,7 +113,7 @@ public function test_dominant_color_has_transparency( string $image_path, array
 	 *
 	 * @dataProvider provider_get_dominant_color
 	 *
-	 * @covers ::dominant_color_img_tag_add_dominant_color
+	 * @covers hooks::dominant_color_img_tag_add_dominant_color
 	 *
 	 * @param string   $image_path Image path.
 	 * @param string[] $expected_color Expected color.
@@ -199,7 +199,7 @@ public function data_dominant_color_img_tag_add_dominant_color_requires_proper_q
 	 *
 	 * @dataProvider data_provider_dominant_color_check_inline_style
 	 *
-	 * @covers ::dominant_color_img_tag_add_dominant_color
+	 * @covers hooks::dominant_color_img_tag_add_dominant_color
 	 *
 	 * @param string $filtered_image The filtered image markup.
 	 *                               Must include `src="%s" width="%d" height="%d"`.
@@ -408,4 +408,105 @@ public function test_dominant_color_render_generator(): void {
 		$this->assertStringContainsString( 'generator', $tag );
 		$this->assertStringContainsString( 'dominant-color-images ' . DOMINANT_COLOR_IMAGES_VERSION, $tag );
 	}
+
+	/**
+	 * @covers Dominant_Color_Image_Editor_GD::get_dominant_color
+	 */
+	public function test_invalid_image_type(): void {
+		$editor = new Dominant_Color_Image_Editor_GD( '/invalid/type' );
+		$result = $editor->get_dominant_color();
+		$this->assertWPError( $result );
+		$this->assertEquals( 'image_editor_dominant_color_error_no_image', $result->get_error_code() );
+	}
+
+	/**
+	 * @covers Dominant_Color_Image_Editor_GD::get_dominant_color
+	 */
+	public function test_corrupted_image_file(): void {
+		$editor = new Dominant_Color_Image_Editor_GD( 'path/to/corrupted/file.jpg' );
+		$result = $editor->get_dominant_color();
+		$this->assertWPError( $result );
+		$this->assertEquals( 'image_editor_dominant_color_error_no_image', $result->get_error_code() );
+	}
+
+	/**
+	 * @covers ::dominant_color_add_inline_style
+	 */
+	public function test_dominant_color_add_inline_style(): void {
+		dominant_color_add_inline_style();
+
+		// Verify the style was registered.
+		global $wp_styles;
+		$this->assertTrue( isset( $wp_styles->registered['dominant-color-styles'] ) );
+
+		// Verify the style was enqueued.
+		$this->assertTrue( wp_style_is( 'dominant-color-styles', 'enqueued' ) );
+
+		// Verify the inline style was added.
+		$inline_styles = $wp_styles->get_data( 'dominant-color-styles', 'after' );
+		$this->assertNotEmpty( $inline_styles );
+		$this->assertStringContainsString(
+			'img[data-dominant-color]:not(.has-transparency) { background-color: var(--dominant-color); }',
+			implode( '', $inline_styles )
+		);
+	}
+
+	/**
+	 * @covers ::dominant_color_admin_inline_style
+	 */
+	public function test_dominant_color_admin_inline_style(): void {
+		dominant_color_admin_inline_style();
+
+		// Verify the style was registered.
+		global $wp_styles;
+		$this->assertTrue( isset( $wp_styles->registered['dominant-color-admin-styles'] ) );
+
+		// Verify the style was enqueued.
+		$this->assertTrue( wp_style_is( 'dominant-color-admin-styles', 'enqueued' ) );
+
+		// Verify the inline style was added.
+		$inline_styles = $wp_styles->get_data( 'dominant-color-admin-styles', 'after' );
+		$this->assertNotEmpty( $inline_styles );
+		$this->assertStringContainsString(
+			'.wp-core-ui .attachment-preview[data-dominant-color]:not(.has-transparency) { background-color: var(--dominant-color); }',
+			implode( '', $inline_styles )
+		);
+	}
+
+	/**
+	 * @covers ::dominant_color_admin_script
+	 */
+	public function test_dominant_color_admin_script(): void {
+		ob_start();
+		dominant_color_admin_script();
+		$output = ob_get_clean();
+
+		// Verify if script tag exists.
+		$this->assertStringEndsWith( '</script>', trim( $output ) );
+
+		// Verify the key elements of the script.
+		$this->assertStringContainsString( 'tmpl.textContent.replace', $output );
+		$this->assertStringContainsString( 'data-dominant-color', $output );
+		$this->assertStringContainsString( 'data-has-transparency', $output );
+		$this->assertStringContainsString( '--dominant-color', $output );
+	}
+
+	/**
+	 * @covers ::dominant_color_prepare_attachment_for_js
+	 */
+	public function test_dominant_color_prepare_attachment_for_js(): void {
+		$attachment = self::factory()->post->create_and_get( array( 'post_type' => 'attachment' ) );
+
+		$meta = array(
+			'dominant_color'   => 'ff0000',
+			'has_transparency' => true,
+		);
+
+		$response = dominant_color_prepare_attachment_for_js( array(), $attachment, $meta );
+
+		$this->assertArrayHasKey( 'dominantColor', $response );
+		$this->assertArrayHasKey( 'hasTransparency', $response );
+		$this->assertEquals( 'ff0000', $response['dominantColor'] );
+		$this->assertTrue( $response['hasTransparency'] );
+	}
 }
diff --git a/plugins/optimization-detective/tests/test-class-od-html-tag-processor.php b/plugins/optimization-detective/tests/test-class-od-html-tag-processor.php
index 0c6953c654..d483efa996 100644
--- a/plugins/optimization-detective/tests/test-class-od-html-tag-processor.php
+++ b/plugins/optimization-detective/tests/test-class-od-html-tag-processor.php
@@ -451,7 +451,7 @@ public function test_next_tag_and_get_xpath( string $document, array $open_tags,
 			$actual_xpath_breadcrumbs_mapping[ $xpath ] = $p->get_breadcrumbs();
 
 			$transitional_xpath = $p->get_xpath();
-			$this->assertRegExp(
+			$this->assertMatchesRegularExpression(
 				'#^/HTML(
 					/HEAD(/\*\[\d+]\[self::\w+])?
 					|