diff --git a/.github/workflows/php-test-plugins.yml b/.github/workflows/php-test-plugins.yml
index 5ebd8738b0..ec1aebda1b 100644
--- a/.github/workflows/php-test-plugins.yml
+++ b/.github/workflows/php-test-plugins.yml
@@ -13,7 +13,6 @@ on:
       - '**/package.json'
       - 'package-lock.json'
       - 'phpunit.xml.dist'
-      - 'tests/multisite.xml'
       - 'composer.json'
       - 'composer.lock'
   pull_request:
@@ -25,7 +24,6 @@ on:
       - '**/package.json'
       - 'package-lock.json'
       - 'phpunit.xml.dist'
-      - 'tests/multisite.xml'
       - 'composer.json'
       - 'composer.lock'
     types:
diff --git a/phpstan.neon.dist b/phpstan.neon.dist
index 9182f7e46a..7d675ac7da 100644
--- a/phpstan.neon.dist
+++ b/phpstan.neon.dist
@@ -5,7 +5,6 @@ parameters:
 	treatPhpDocTypesAsCertain: false
 	paths:
 		- plugins
-		- tests
 		- performance.php
 		- plugins/performance-lab/load.php
 	bootstrapFiles:
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index 4b09476b23..dabb920a24 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -1,7 +1,7 @@
 <phpunit
 	colors="true"
 	backupGlobals="false"
-	bootstrap="tests/bootstrap.php"
+	bootstrap="tools/phpunit/bootstrap.php"
 	convertErrorsToExceptions="true"
 	convertNoticesToExceptions="true"
 	convertWarningsToExceptions="true"
diff --git a/plugins/auto-sizes/tests/bootstrap.php b/plugins/auto-sizes/tests/bootstrap.php
deleted file mode 100644
index 8c2e84094c..0000000000
--- a/plugins/auto-sizes/tests/bootstrap.php
+++ /dev/null
@@ -1,10 +0,0 @@
-<?php
-/**
- * Test Bootstrap for Auto Sizes.
- *
- * @package auto-sizes
- */
-
-// Require the suggested plugins.
-require_once __DIR__ . '/../../optimization-detective/load.php';
-require_once __DIR__ . '/../../image-prioritizer/load.php';
diff --git a/tests/data/images/leaves.jpg b/plugins/auto-sizes/tests/data/images/leaves.jpg
similarity index 100%
rename from tests/data/images/leaves.jpg
rename to plugins/auto-sizes/tests/data/images/leaves.jpg
diff --git a/plugins/dominant-color-images/tests/data/class-testcase.php b/plugins/dominant-color-images/tests/data/class-testcase.php
index ffcb25e738..6fbb8083ef 100644
--- a/plugins/dominant-color-images/tests/data/class-testcase.php
+++ b/plugins/dominant-color-images/tests/data/class-testcase.php
@@ -13,85 +13,85 @@ abstract class TestCase extends WP_UnitTestCase {
 	public function provider_get_dominant_color(): array {
 		return array(
 			'animated_gif'  => array(
-				'image_path'            => __DIR__ . '/images/animated.gif',
+				'image_path'            => TESTS_PLUGIN_DIR . '/tests/data/images/animated.gif',
 				'expected_color'        => array( '874e4e', '864e4e', 'df7f7f' ),
 				'expected_transparency' => true,
 			),
 			'red_jpg'       => array(
-				'image_path'            => __DIR__ . '/images/red.jpg',
+				'image_path'            => TESTS_PLUGIN_DIR . '/tests/data/images/red.jpg',
 				'expected_color'        => array( 'ff0000', 'fe0000' ),
 				'expected_transparency' => false,
 			),
 			'green_jpg'     => array(
-				'image_path'            => __DIR__ . '/images/green.jpg',
+				'image_path'            => TESTS_PLUGIN_DIR . '/tests/data/images/green.jpg',
 				'expected_color'        => array( '00ff00', '00ff01', '02ff01' ),
 				'expected_transparency' => false,
 			),
 			'white_jpg'     => array(
-				'image_path'            => __DIR__ . '/images/white.jpg',
+				'image_path'            => TESTS_PLUGIN_DIR . '/tests/data/images/white.jpg',
 				'expected_color'        => array( 'ffffff' ),
 				'expected_transparency' => false,
 			),
 
 			'red_gif'       => array(
-				'image_path'            => __DIR__ . '/images/red.gif',
+				'image_path'            => TESTS_PLUGIN_DIR . '/tests/data/images/red.gif',
 				'expected_color'        => array( 'ff0000' ),
 				'expected_transparency' => false,
 			),
 			'green_gif'     => array(
-				'image_path'            => __DIR__ . '/images/green.gif',
+				'image_path'            => TESTS_PLUGIN_DIR . '/tests/data/images/green.gif',
 				'expected_color'        => array( '00ff00' ),
 				'expected_transparency' => false,
 			),
 			'white_gif'     => array(
-				'image_path'            => __DIR__ . '/images/white.gif',
+				'image_path'            => TESTS_PLUGIN_DIR . '/tests/data/images/white.gif',
 				'expected_color'        => array( 'ffffff' ),
 				'expected_transparency' => false,
 			),
 			'trans_gif'     => array(
-				'image_path'            => __DIR__ . '/images/trans.gif',
+				'image_path'            => TESTS_PLUGIN_DIR . '/tests/data/images/trans.gif',
 				'expected_color'        => array( '5a5a5a', '020202' ),
 				'expected_transparency' => true,
 			),
 
 			'red_png'       => array(
-				'image_path'            => __DIR__ . '/images/red.png',
+				'image_path'            => TESTS_PLUGIN_DIR . '/tests/data/images/red.png',
 				'expected_color'        => array( 'ff0000' ),
 				'expected_transparency' => false,
 			),
 			'green_png'     => array(
-				'image_path'            => __DIR__ . '/images/green.png',
+				'image_path'            => TESTS_PLUGIN_DIR . '/tests/data/images/green.png',
 				'expected_color'        => array( '00ff00' ),
 				'expected_transparency' => false,
 			),
 			'white_png'     => array(
-				'image_path'            => __DIR__ . '/images/white.png',
+				'image_path'            => TESTS_PLUGIN_DIR . '/tests/data/images/white.png',
 				'expected_color'        => array( 'ffffff' ),
 				'expected_transparency' => false,
 			),
 			'trans_png'     => array(
-				'image_path'            => __DIR__ . '/images/trans.png',
+				'image_path'            => TESTS_PLUGIN_DIR . '/tests/data/images/trans.png',
 				'expected_color'        => array( '000000' ),
 				'expected_transparency' => true,
 			),
 
 			'red_webp'      => array(
-				'image_path'            => __DIR__ . '/images/red.webp',
+				'image_path'            => TESTS_PLUGIN_DIR . '/tests/data/images/red.webp',
 				'expected_color'        => array( 'ff0000' ),
 				'expected_transparency' => false,
 			),
 			'green_webp'    => array(
-				'image_path'            => __DIR__ . '/images/green.webp',
+				'image_path'            => TESTS_PLUGIN_DIR . '/tests/data/images/green.webp',
 				'expected_color'        => array( '00ff00' ),
 				'expected_transparency' => false,
 			),
 			'white_webp'    => array(
-				'image_path'            => __DIR__ . '/images/white.webp',
+				'image_path'            => TESTS_PLUGIN_DIR . '/tests/data/images/white.webp',
 				'expected_color'        => array( 'ffffff' ),
 				'expected_transparency' => false,
 			),
 			'trans_webp'    => array(
-				'image_path'            => __DIR__ . '/images/trans.webp',
+				'image_path'            => TESTS_PLUGIN_DIR . '/tests/data/images/trans.webp',
 				'expected_color'        => array( '000000' ),
 				'expected_transparency' => true,
 			),
@@ -101,7 +101,7 @@ public function provider_get_dominant_color(): array {
 				'expected_transparency' => false,
 			),
 			'half_opaque'   => array(
-				'image_path'            => __DIR__ . '/images/half-opaque.png',
+				'image_path'            => TESTS_PLUGIN_DIR . '/tests/data/images/half-opaque.png',
 				'expected_color'        => array( '7e7e7e' ),
 				'expected_transparency' => true,
 			),
@@ -116,10 +116,10 @@ public function provider_get_dominant_color(): array {
 	public function provider_get_dominant_color_invalid_images(): array {
 		return array(
 			'tiff' => array(
-				'image_path' => __DIR__ . '/images/test-image.tiff',
+				'image_path' => TESTS_PLUGIN_DIR . '/tests/data/images/test-image.tiff',
 			),
 			'bmp'  => array(
-				'image_path' => __DIR__ . '/images/test-image.bmp',
+				'image_path' => TESTS_PLUGIN_DIR . '/tests/data/images/test-image.bmp',
 			),
 		);
 	}
@@ -132,10 +132,10 @@ public function provider_get_dominant_color_invalid_images(): array {
 	public function provider_get_dominant_color_none_images(): array {
 		return array(
 			'pdf' => array(
-				'files_path' => __DIR__ . '/images/wordpress-gsoc-flyer.pdf',
+				'files_path' => TESTS_PLUGIN_DIR . '/tests/data/images/wordpress-gsoc-flyer.pdf',
 			),
 			'mp4' => array(
-				'files_path' => __DIR__ . '/images/small-video.mp4',
+				'files_path' => TESTS_PLUGIN_DIR . '/tests/data/images/small-video.mp4',
 			),
 		);
 	}
diff --git a/tests/data/images/balloons.webp b/plugins/dominant-color-images/tests/data/images/balloons.webp
similarity index 100%
rename from tests/data/images/balloons.webp
rename to plugins/dominant-color-images/tests/data/images/balloons.webp
diff --git a/plugins/dominant-color-images/tests/test-dominant-color.php b/plugins/dominant-color-images/tests/test-dominant-color.php
index 7214f765cc..9c321c9c8e 100644
--- a/plugins/dominant-color-images/tests/test-dominant-color.php
+++ b/plugins/dominant-color-images/tests/test-dominant-color.php
@@ -162,7 +162,7 @@ public function test_tag_add_adjust_to_image_attributes( string $image_path, arr
 	 * @param bool   $expected Whether the dominant color should be added.
 	 */
 	public function test_dominant_color_img_tag_add_dominant_color_requires_proper_quotes( string $image, bool $expected ): void {
-		$attachment_id = self::factory()->attachment->create_upload_object( __DIR__ . '/data/images/red.jpg' );
+		$attachment_id = self::factory()->attachment->create_upload_object( TESTS_PLUGIN_DIR . '/tests/data/images/red.jpg' );
 		wp_maybe_generate_attachment_metadata( get_post( $attachment_id ) );
 
 		$image_url = wp_get_attachment_image_url( $attachment_id );
@@ -206,7 +206,7 @@ public function data_dominant_color_img_tag_add_dominant_color_requires_proper_q
 	 * @param string $expected       The expected style attribute and value.
 	 */
 	public function test_dominant_color_img_tag_add_dominant_color_should_add_dominant_color_inline_style( string $filtered_image, string $expected ): void {
-		$attachment_id = self::factory()->attachment->create_upload_object( __DIR__ . '/data/images/red.jpg' );
+		$attachment_id = self::factory()->attachment->create_upload_object( TESTS_PLUGIN_DIR . '/tests/data/images/red.jpg' );
 		wp_maybe_generate_attachment_metadata( get_post( $attachment_id ) );
 
 		list( $src, $width, $height ) = wp_get_attachment_image_src( $attachment_id );
@@ -246,7 +246,7 @@ public function data_provider_dominant_color_check_inline_style(): array {
 	 * @param string $expected   The expected style attribute and value.
 	 */
 	public function test_dominant_color_update_attachment_image_attributes( string $style_attr, string $expected ): void {
-		$attachment_id = self::factory()->attachment->create_upload_object( __DIR__ . '/data/images/red.jpg' );
+		$attachment_id = self::factory()->attachment->create_upload_object( TESTS_PLUGIN_DIR . '/tests/data/images/red.jpg' );
 
 		$attachment_image = wp_get_attachment_image( $attachment_id, 'full', false, array( 'style' => $style_attr ) );
 		$this->assertStringContainsString( $expected, $attachment_image );
diff --git a/plugins/embed-optimizer/tests/bootstrap.php b/plugins/embed-optimizer/tests/bootstrap.php
index 260eb784d5..43203c20b0 100644
--- a/plugins/embed-optimizer/tests/bootstrap.php
+++ b/plugins/embed-optimizer/tests/bootstrap.php
@@ -6,4 +6,7 @@
  */
 
 // Require the suggested plugin.
-require_once __DIR__ . '/../../optimization-detective/load.php';
+require_once TESTS_REPO_ROOT_DIR . '/plugins/optimization-detective/load.php';
+
+// Load the test helpers.
+require_once TESTS_REPO_ROOT_DIR . '/plugins/optimization-detective/tests/class-optimization-detective-test-helpers.php';
diff --git a/plugins/image-prioritizer/tests/bootstrap.php b/plugins/image-prioritizer/tests/bootstrap.php
new file mode 100644
index 0000000000..c151e78081
--- /dev/null
+++ b/plugins/image-prioritizer/tests/bootstrap.php
@@ -0,0 +1,9 @@
+<?php
+/**
+ * Test Bootstrap for Image Prioritizer.
+ *
+ * @package image-prioritizer
+ */
+
+// Load the test helpers.
+require_once TESTS_REPO_ROOT_DIR . '/plugins/optimization-detective/tests/class-optimization-detective-test-helpers.php';
diff --git a/tests/data/images/car.jpeg b/plugins/image-prioritizer/tests/data/images/car.jpeg
similarity index 100%
rename from tests/data/images/car.jpeg
rename to plugins/image-prioritizer/tests/data/images/car.jpeg
diff --git a/plugins/optimization-detective/tests/bootstrap.php b/plugins/optimization-detective/tests/bootstrap.php
new file mode 100644
index 0000000000..745d91620a
--- /dev/null
+++ b/plugins/optimization-detective/tests/bootstrap.php
@@ -0,0 +1,9 @@
+<?php
+/**
+ * Test Bootstrap for Optimiztaion Detective.
+ *
+ * @package optimization-detective
+ */
+
+// Load the test helpers.
+require_once TESTS_REPO_ROOT_DIR . '/plugins/optimization-detective/tests/class-optimization-detective-test-helpers.php';
diff --git a/tests/class-optimization-detective-test-helpers.php b/plugins/optimization-detective/tests/class-optimization-detective-test-helpers.php
similarity index 99%
rename from tests/class-optimization-detective-test-helpers.php
rename to plugins/optimization-detective/tests/class-optimization-detective-test-helpers.php
index 84be07a41e..dc06730ab9 100644
--- a/tests/class-optimization-detective-test-helpers.php
+++ b/plugins/optimization-detective/tests/class-optimization-detective-test-helpers.php
@@ -2,7 +2,7 @@
 /**
  * Helper trait for Optimization Detective tests.
  *
- * @package performance-lab
+ * @package optimization-detective
  *
  * @noinspection PhpDocMissingThrowsInspection
  * @noinspection PhpUnhandledExceptionInspection
diff --git a/plugins/optimization-detective/tests/test-uninstall.php b/plugins/optimization-detective/tests/test-uninstall.php
index b5e9379d54..a290d4d85e 100644
--- a/plugins/optimization-detective/tests/test-uninstall.php
+++ b/plugins/optimization-detective/tests/test-uninstall.php
@@ -24,7 +24,7 @@ public static function set_up_before_class(): void {
 	 * Load uninstall.php.
 	 */
 	private function require_uninstall(): void {
-		require __DIR__ . '/../../../plugins/optimization-detective/uninstall.php';
+		require TESTS_PLUGIN_DIR . '/uninstall.php';
 	}
 
 	/**
diff --git a/plugins/speculation-rules/tests/test-speculation-rules-uninstall.php b/plugins/speculation-rules/tests/test-speculation-rules-uninstall.php
index 3f4b73b2b1..2628bf3cfa 100644
--- a/plugins/speculation-rules/tests/test-speculation-rules-uninstall.php
+++ b/plugins/speculation-rules/tests/test-speculation-rules-uninstall.php
@@ -24,7 +24,7 @@ public static function set_up_before_class(): void {
 	 * Load uninstall.php.
 	 */
 	private function require_uninstall(): void {
-		require __DIR__ . '/../../../plugins/speculation-rules/uninstall.php';
+		require TESTS_PLUGIN_DIR . '/uninstall.php';
 	}
 
 	/**
diff --git a/plugins/webp-uploads/tests/data/images/balloons.webp b/plugins/webp-uploads/tests/data/images/balloons.webp
new file mode 100644
index 0000000000..f3db76a9bc
Binary files /dev/null and b/plugins/webp-uploads/tests/data/images/balloons.webp differ
diff --git a/plugins/webp-uploads/tests/data/images/car.jpeg b/plugins/webp-uploads/tests/data/images/car.jpeg
new file mode 100644
index 0000000000..583967594f
Binary files /dev/null and b/plugins/webp-uploads/tests/data/images/car.jpeg differ
diff --git a/tests/data/images/dice.png b/plugins/webp-uploads/tests/data/images/dice.png
similarity index 100%
rename from tests/data/images/dice.png
rename to plugins/webp-uploads/tests/data/images/dice.png
diff --git a/tests/data/images/earth.gif b/plugins/webp-uploads/tests/data/images/earth.gif
similarity index 100%
rename from tests/data/images/earth.gif
rename to plugins/webp-uploads/tests/data/images/earth.gif
diff --git a/tests/data/images/image.jpeg b/plugins/webp-uploads/tests/data/images/image.jpeg
similarity index 100%
rename from tests/data/images/image.jpeg
rename to plugins/webp-uploads/tests/data/images/image.jpeg
diff --git a/tests/data/images/image.jpg b/plugins/webp-uploads/tests/data/images/image.jpg
similarity index 100%
rename from tests/data/images/image.jpg
rename to plugins/webp-uploads/tests/data/images/image.jpg
diff --git a/plugins/webp-uploads/tests/data/images/leaves.jpg b/plugins/webp-uploads/tests/data/images/leaves.jpg
new file mode 100644
index 0000000000..447e5cfa3a
Binary files /dev/null and b/plugins/webp-uploads/tests/data/images/leaves.jpg differ
diff --git a/tests/data/images/paint.jpeg b/plugins/webp-uploads/tests/data/images/paint.jpeg
similarity index 100%
rename from tests/data/images/paint.jpeg
rename to plugins/webp-uploads/tests/data/images/paint.jpeg
diff --git a/tools/phpcs/phpcs.ruleset.xml b/tools/phpcs/phpcs.ruleset.xml
index 12e24ed1ef..094927b585 100644
--- a/tools/phpcs/phpcs.ruleset.xml
+++ b/tools/phpcs/phpcs.ruleset.xml
@@ -53,12 +53,15 @@
 	</rule>
 	<rule ref="WordPress.WP.AlternativeFunctions.file_get_contents_file_get_contents">
 		<exclude-pattern>tests/*</exclude-pattern>
+		<exclude-pattern>tools/phpunit/*</exclude-pattern>
 	</rule>
 	<rule ref="WordPress.Security.EscapeOutput.OutputNotEscaped">
 		<exclude-pattern>tests/*</exclude-pattern>
+		<exclude-pattern>tools/phpunit/*</exclude-pattern>
 	</rule>
 	<rule ref="WordPress.WP.AlternativeFunctions.unlink_unlink">
 		<exclude-pattern>tests/*</exclude-pattern>
+		<exclude-pattern>tools/phpunit/*</exclude-pattern>
 	</rule>
 	<rule ref="WordPress.WP.GlobalVariablesOverride.Prohibited">
 		<exclude-pattern>tests/*</exclude-pattern>
diff --git a/tools/phpstan/constants.php b/tools/phpstan/constants.php
index ae469bf4dc..bae8b53db4 100644
--- a/tools/phpstan/constants.php
+++ b/tools/phpstan/constants.php
@@ -6,6 +6,7 @@
  */
 
 define( 'TESTS_PLUGIN_DIR', './' );
+define( 'TESTS_REPO_ROOT_DIR', './' );
 define( 'WPINC', 'wp-includes' );
 
 define( 'SPECULATION_RULES_VERSION', '0.0.0' );
diff --git a/tests/bootstrap.php b/tools/phpunit/bootstrap.php
similarity index 79%
rename from tests/bootstrap.php
rename to tools/phpunit/bootstrap.php
index b2a0fc08a3..b845c92fde 100644
--- a/tests/bootstrap.php
+++ b/tools/phpunit/bootstrap.php
@@ -5,18 +5,18 @@
  * @package performance-lab
  */
 
-define( 'TESTS_PLUGIN_DIR', dirname( __DIR__ ) );
+define( 'TESTS_REPO_ROOT_DIR', dirname( __DIR__, 2 ) );
 
 // Determine correct location for plugins directory to use.
 if ( false !== getenv( 'WP_PLUGIN_DIR' ) ) {
 	define( 'WP_PLUGIN_DIR', getenv( 'WP_PLUGIN_DIR' ) );
 } else {
-	define( 'WP_PLUGIN_DIR', dirname( TESTS_PLUGIN_DIR ) );
+	define( 'WP_PLUGIN_DIR', dirname( TESTS_REPO_ROOT_DIR ) );
 }
 
 // Load Composer dependencies if applicable.
-if ( file_exists( TESTS_PLUGIN_DIR . '/vendor/autoload.php' ) ) {
-	require_once TESTS_PLUGIN_DIR . '/vendor/autoload.php';
+if ( file_exists( TESTS_REPO_ROOT_DIR . '/vendor/autoload.php' ) ) {
+	require_once TESTS_REPO_ROOT_DIR . '/vendor/autoload.php';
 }
 
 // Detect where to load the WordPress tests environment from.
@@ -26,8 +26,8 @@
 	$_test_root = getenv( 'WP_DEVELOP_DIR' ) . '/tests/phpunit';
 } elseif ( false !== getenv( 'WP_PHPUNIT__DIR' ) ) {
 	$_test_root = getenv( 'WP_PHPUNIT__DIR' );
-} elseif ( file_exists( TESTS_PLUGIN_DIR . '/../../../../tests/phpunit/includes/functions.php' ) ) {
-	$_test_root = TESTS_PLUGIN_DIR . '/../../../../tests/phpunit';
+} elseif ( file_exists( TESTS_REPO_ROOT_DIR . '/../../../../tests/phpunit/includes/functions.php' ) ) {
+	$_test_root = TESTS_REPO_ROOT_DIR . '/../../../../tests/phpunit';
 } else { // Fallback.
 	$_test_root = '/tmp/wordpress-tests-lib';
 }
@@ -47,7 +47,7 @@
 	if (
 		'--testsuite' === $arg &&
 		isset( $_SERVER['argv'][ $index + 1 ] ) &&
-		file_exists( TESTS_PLUGIN_DIR . '/plugins/' . $_SERVER['argv'][ $index + 1 ] )
+		file_exists( TESTS_REPO_ROOT_DIR . '/plugins/' . $_SERVER['argv'][ $index + 1 ] )
 	) {
 		$plugin_name = $_SERVER['argv'][ $index + 1 ];
 	}
@@ -58,13 +58,15 @@
 	$plugin_name = 'performance-lab';
 }
 
+define( 'TESTS_PLUGIN_DIR', TESTS_REPO_ROOT_DIR . "/plugins/$plugin_name" );
+
 /**
  * Load plugin bootstrap and any dependencies.
  *
  * @param string $plugin_name Plugin slug to load.
  */
 $load_plugin = static function ( string $plugin_name ) use ( &$load_plugin ): void {
-	$plugin_test_path = TESTS_PLUGIN_DIR . '/plugins/' . $plugin_name;
+	$plugin_test_path = TESTS_REPO_ROOT_DIR . '/plugins/' . $plugin_name;
 	if ( file_exists( $plugin_test_path . '/' . $plugin_name . '.php' ) ) {
 		$plugin_file = $plugin_test_path . '/' . $plugin_name . '.php';
 	} elseif ( file_exists( $plugin_test_path . '/load.php' ) ) {
@@ -102,9 +104,9 @@ static function () use ( $load_plugin, $plugin_name ): void {
 	tests_add_filter(
 		'plugins_loaded',
 		static function () use ( $plugin_name ): void {
-			require_once TESTS_PLUGIN_DIR . '/plugins/' . $plugin_name . '/includes/admin/load.php';
-			require_once TESTS_PLUGIN_DIR . '/plugins/' . $plugin_name . '/includes/admin/server-timing.php';
-			require_once TESTS_PLUGIN_DIR . '/plugins/' . $plugin_name . '/includes/admin/plugins.php';
+			require_once TESTS_REPO_ROOT_DIR . '/plugins/' . $plugin_name . '/includes/admin/load.php';
+			require_once TESTS_REPO_ROOT_DIR . '/plugins/' . $plugin_name . '/includes/admin/server-timing.php';
+			require_once TESTS_REPO_ROOT_DIR . '/plugins/' . $plugin_name . '/includes/admin/plugins.php';
 		},
 		1
 	);
@@ -127,8 +129,5 @@ static function ( bool $passthrough ): bool {
 	}
 );
 
-// Require helper classes.
-require_once __DIR__ . '/class-optimization-detective-test-helpers.php';
-
 // Start up the WP testing environment.
 require $_test_root . '/includes/bootstrap.php';