diff --git a/docs/checks.md b/docs/checks.md
index 11662a607..ceee2ce5b 100644
--- a/docs/checks.md
+++ b/docs/checks.md
@@ -16,6 +16,7 @@
 | plugin_uninstall | plugin_repo | Checks related to plugin uninstallation. | [Learn more](https://developer.wordpress.org/plugins/plugin-basics/uninstall-methods/#method-2-uninstall-php) |
 | external_admin_menu_links | plugin_repo | Detects external URLs used in top-level WordPress admin menu, which disrupts the expected user experience. | [Learn more](https://developer.wordpress.org/plugins/wordpress-org/detailed-plugin-guidelines/#11-plugins-should-not-hijack-the-admin) |
 | wp_functions_compatibility | plugin_repo | Checks whether WordPress functions used by the plugin are compatible with the declared minimum supported WordPress version ("Requires at least"). | [Learn more](https://developer.wordpress.org/plugins/plugin-basics/header-requirements/#header-fields) |
+| personal_data_eraser | plugin_repo | Detects plugins that store personal data without registering a personal data eraser for GDPR compliance. | [Learn more](https://developer.wordpress.org/plugins/privacy/adding-the-personal-data-eraser-to-your-plugin/) |
 | plugin_review_phpcs | plugin_repo | Runs PHP_CodeSniffer to detect certain best practices plugins should follow for submission on WordPress.org, including heredoc usage detection. | [Learn more](https://developer.wordpress.org/plugins/plugin-basics/best-practices/) |
 | direct_db_queries | security, plugin_repo | Checks the usage of direct database queries, which should be avoided. | [Learn more](https://developer.wordpress.org/apis/database/) |
 | direct_db | security, plugin_repo | Checks the escaping in direct database queries. | [Learn more](https://developer.wordpress.org/apis/database/) |
diff --git a/includes/Checker/Checks/Plugin_Repo/Personal_Data_Eraser_Check.php b/includes/Checker/Checks/Plugin_Repo/Personal_Data_Eraser_Check.php
new file mode 100644
index 000000000..cc0c9d2b8
--- /dev/null
+++ b/includes/Checker/Checks/Plugin_Repo/Personal_Data_Eraser_Check.php
@@ -0,0 +1,464 @@
+<?php
+/**
+ * Class Personal_Data_Eraser_Check.
+ *
+ * @package plugin-check
+ */
+
+namespace WordPress\Plugin_Check\Checker\Checks\Plugin_Repo;
+
+use WordPress\Plugin_Check\Checker\Check_Categories;
+use WordPress\Plugin_Check\Checker\Check_Result;
+use WordPress\Plugin_Check\Checker\Checks\Abstract_File_Check;
+use WordPress\Plugin_Check\Traits\Amend_Check_Result;
+use WordPress\Plugin_Check\Traits\Experimental_Check;
+
+/**
+ * Check to detect personal data handling without a registered eraser callback.
+ *
+ * Plugins that collect or store personal data are expected to register an
+ * eraser callback via the `wp_privacy_personal_data_erasers` filter so that
+ * WordPress's built-in Personal Data Removal tool can delete the plugin's
+ * data on behalf of a user who submits a removal request.
+ *
+ * @since 2.0.0
+ * @link https://developer.wordpress.org/plugins/privacy/adding-the-personal-data-eraser-to-your-plugin/
+ */
+class Personal_Data_Eraser_Check extends Abstract_File_Check {
+
+	use Amend_Check_Result;
+	use Experimental_Check;
+
+	/**
+	 * Functions that are strong indicators a plugin is storing personal data.
+	 *
+	 * @since 2.0.0
+	 * @var array
+	 */
+	const PERSONAL_DATA_FUNCTIONS = array(
+		'add_user_meta',
+		'update_user_meta',
+		'add_comment_meta',
+		'update_comment_meta',
+	);
+
+	/**
+	 * $wpdb methods that write data and are strong indicators of personal data storage.
+	 *
+	 * @since 2.0.0
+	 * @var array
+	 */
+	const WPDB_METHODS = array(
+		'insert',
+		'update',
+		'replace',
+	);
+
+	/**
+	 * The filter used to register a personal data eraser.
+	 *
+	 * @since 2.0.0
+	 * @var string
+	 */
+	const ERASER_FILTER = 'wp_privacy_personal_data_erasers';
+
+	/**
+	 * Gets the categories for the check.
+	 *
+	 * Every check must have at least one category.
+	 *
+	 * @since 2.0.0
+	 *
+	 * @return array The categories for the check.
+	 */
+	public function get_categories() {
+		return array( Check_Categories::CATEGORY_PLUGIN_REPO );
+	}
+
+	/**
+	 * Amends the given result by running the check on the given list of files.
+	 *
+	 * @since 2.0.0
+	 *
+	 * @param Check_Result $result The check result to amend, including the plugin context to check.
+	 * @param array        $files  List of absolute file paths.
+	 */
+	protected function check_files( Check_Result $result, array $files ) {
+		$php_files = self::filter_files_by_extension( $files, 'php' );
+		$php_files = $this->filter_out_test_paths( $php_files, $result->plugin()->path() );
+
+		$this->check_for_missing_eraser( $result, $php_files );
+	}
+
+	/**
+	 * Checks whether the plugin handles personal data but omits the eraser filter.
+	 *
+	 * The check is intentionally a two-step process:
+	 * 1. Confirm the plugin has at least one personal-data storage call.
+	 * 2. Only then verify whether it registers the eraser filter.
+	 *
+	 * This avoids false positives for plugins that do not touch personal data at all.
+	 *
+	 * @since 2.0.0
+	 *
+	 * @param Check_Result $result    The check result to amend.
+	 * @param array        $php_files List of absolute PHP file paths.
+	 */
+	protected function check_for_missing_eraser( Check_Result $result, array $php_files ) {
+		// Step 1: detect personal data signals across all plugin PHP files.
+		$line        = 0;
+		$signal_file = $this->find_file_with_personal_data_signal( $php_files, $line );
+
+		if ( null === $signal_file ) {
+			// No personal data handling detected — nothing to warn about.
+			return;
+		}
+
+		// Step 2: check if the plugin already registers a personal data eraser.
+		if ( $this->has_eraser_registration( $php_files ) ) {
+			// Eraser is registered — no issue.
+			return;
+		}
+
+		// Personal data is handled but no eraser is registered: emit a warning.
+		$this->add_result_warning_for_file(
+			$result,
+			__( 'Personal data was detected in this plugin but no data eraser has been registered. Plugins that store personal data should implement a data eraser via the <code>wp_privacy_personal_data_erasers</code> filter so that site administrators can fulfill data removal requests.', 'plugin-check' ),
+			'missing_personal_data_eraser',
+			$signal_file,
+			$line,
+			0,
+			'https://developer.wordpress.org/plugins/privacy/adding-the-personal-data-eraser-to-your-plugin/',
+			5
+		);
+	}
+
+	/**
+	 * Finds the first file that contains a personal data signal.
+	 *
+	 * @since 2.0.0
+	 *
+	 * @param array $php_files List of absolute PHP file paths.
+	 * @param int   $line      Reference to store the line of the detected signal.
+	 * @return string|null The file path, or null if no signal was found.
+	 */
+	private function find_file_with_personal_data_signal( array $php_files, int &$line ) {
+		foreach ( $php_files as $file ) {
+			$source = file_get_contents( $file );
+			if ( false === $source || '' === $source ) {
+				continue;
+			}
+
+			$tokens = token_get_all( $source );
+			$count  = count( $tokens );
+
+			for ( $i = 0; $i < $count; $i++ ) {
+				if ( $this->is_personal_data_function_call( $tokens, $i ) || $this->is_wpdb_method_call( $tokens, $i ) ) {
+					$line = (int) $tokens[ $i ][2];
+					return $file;
+				}
+			}
+		}
+
+		return null;
+	}
+
+	/**
+	 * Checks whether the plugin registers a personal data eraser.
+	 *
+	 * @since 2.0.0
+	 *
+	 * @param array $php_files List of absolute PHP file paths.
+	 * @return bool True if an eraser is registered, false otherwise.
+	 */
+	private function has_eraser_registration( array $php_files ): bool {
+		foreach ( $php_files as $file ) {
+			$source = file_get_contents( $file );
+			if ( false === $source || '' === $source ) {
+				continue;
+			}
+
+			$tokens = token_get_all( $source );
+			$count  = count( $tokens );
+
+			for ( $i = 0; $i < $count; $i++ ) {
+				if ( $this->is_eraser_filter_registration( $tokens, $i ) ) {
+					return true;
+				}
+			}
+		}
+
+		return false;
+	}
+
+	/**
+	 * Determines whether the token at the given index is a personal data function call.
+	 *
+	 * @since 2.0.0
+	 *
+	 * @param array $tokens Token stream from token_get_all().
+	 * @param int   $index  Index of the token to inspect.
+	 * @return bool True if the token is a personal data function call.
+	 */
+	private function is_personal_data_function_call( array $tokens, int $index ): bool {
+		$token = $tokens[ $index ];
+
+		if ( ! is_array( $token ) || T_STRING !== $token[0] ) {
+			return false;
+		}
+
+		$name = strtolower( $token[1] );
+
+		if ( ! in_array( $name, self::PERSONAL_DATA_FUNCTIONS, true ) ) {
+			return false;
+		}
+
+		if ( ! $this->is_global_function_call( $tokens, $index ) ) {
+			return false;
+		}
+
+		$next = $this->get_next_significant_token_index( $tokens, $index );
+
+		return null !== $next && '(' === $tokens[ $next ];
+	}
+
+	/**
+	 * Determines whether the token at the given index is a $wpdb write method call.
+	 *
+	 * @since 2.0.0
+	 *
+	 * @param array $tokens Token stream from token_get_all().
+	 * @param int   $index  Index of the token to inspect.
+	 * @return bool True if the token is a $wpdb write method call.
+	 */
+	private function is_wpdb_method_call( array $tokens, int $index ): bool {
+		$token = $tokens[ $index ];
+
+		if ( ! is_array( $token ) || T_VARIABLE !== $token[0] || '$wpdb' !== $token[1] ) {
+			return false;
+		}
+
+		$arrow_index = $this->get_next_significant_token_index( $tokens, $index );
+
+		if ( null === $arrow_index ) {
+			return false;
+		}
+
+		$method_index = $this->get_next_significant_token_index( $tokens, $arrow_index );
+
+		if ( null === $method_index ) {
+			return false;
+		}
+
+		$arrow_token  = $tokens[ $arrow_index ];
+		$method_token = $tokens[ $method_index ];
+
+		if (
+			! is_array( $arrow_token )
+			|| T_OBJECT_OPERATOR !== $arrow_token[0]
+			|| ! is_array( $method_token )
+			|| T_STRING !== $method_token[0]
+			|| ! in_array( strtolower( $method_token[1] ), self::WPDB_METHODS, true )
+		) {
+			return false;
+		}
+
+		// Confirm the method is actually invoked with a call.
+		$call_index = $this->get_next_significant_token_index( $tokens, $method_index );
+
+		return null !== $call_index && '(' === $tokens[ $call_index ];
+	}
+
+	/**
+	 * Determines whether the token at the given index registers a personal data eraser.
+	 *
+	 * @since 2.0.0
+	 *
+	 * @param array $tokens Token stream from token_get_all().
+	 * @param int   $index  Index of the token to inspect.
+	 * @return bool True if the token registers a personal data eraser.
+	 */
+	private function is_eraser_filter_registration( array $tokens, int $index ): bool {
+		$token = $tokens[ $index ];
+
+		if ( ! is_array( $token ) || T_STRING !== $token[0] || 'add_filter' !== strtolower( $token[1] ) ) {
+			return false;
+		}
+
+		if ( ! $this->is_global_function_call( $tokens, $index ) ) {
+			return false;
+		}
+
+		$open_paren = $this->get_next_significant_token_index( $tokens, $index );
+
+		if ( null === $open_paren || '(' !== $tokens[ $open_paren ] ) {
+			return false;
+		}
+
+		$arg_index = $this->get_next_significant_token_index( $tokens, $open_paren );
+
+		if ( null === $arg_index ) {
+			return false;
+		}
+
+		$arg = $tokens[ $arg_index ];
+
+		if ( ! is_array( $arg ) || T_CONSTANT_ENCAPSED_STRING !== $arg[0] ) {
+			return false;
+		}
+
+		return trim( $arg[1], "\"' \t\n\r\0\x0B" ) === self::ERASER_FILTER;
+	}
+
+	/**
+	 * Determines whether the token at the given index is a call to a global function.
+	 *
+	 * Excludes method calls, static calls, function declarations, and namespaced
+	 * function calls.
+	 *
+	 * @since 2.0.0
+	 *
+	 * @param array $tokens Token stream from token_get_all().
+	 * @param int   $index  Index of the token to inspect.
+	 * @return bool True if the token is a global function call.
+	 */
+	private function is_global_function_call( array $tokens, int $index ): bool {
+		$previous_index = $this->get_previous_significant_token_index( $tokens, $index );
+
+		if ( null === $previous_index ) {
+			return true;
+		}
+
+		$previous_token = $tokens[ $previous_index ];
+
+		if ( ! is_array( $previous_token ) ) {
+			return ! is_string( $previous_token ) || '(' !== $previous_token;
+		}
+
+		if ( in_array( $previous_token[0], array( T_FUNCTION, T_NEW, T_OBJECT_OPERATOR, T_DOUBLE_COLON ), true ) ) {
+			return false;
+		}
+
+		if ( T_NS_SEPARATOR === $previous_token[0] ) {
+			$before_namespace_index = $this->get_previous_significant_token_index( $tokens, $previous_index );
+
+			if ( null === $before_namespace_index ) {
+				return true;
+			}
+
+			$before_namespace_token = $tokens[ $before_namespace_index ];
+
+			if ( is_array( $before_namespace_token ) && in_array( $before_namespace_token[0], array( T_STRING, T_NAMESPACE ), true ) ) {
+				return false;
+			}
+		}
+
+		return true;
+	}
+
+	/**
+	 * Gets the index of the next significant token, skipping whitespace and comments.
+	 *
+	 * @since 2.0.0
+	 *
+	 * @param array $tokens Token stream from token_get_all().
+	 * @param int   $index  Index to start scanning from.
+	 * @return int|null The next significant token index, or null if none exists.
+	 */
+	private function get_next_significant_token_index( array $tokens, int $index ): ?int {
+		$count = count( $tokens );
+
+		for ( $i = $index + 1; $i < $count; $i++ ) {
+			$token = $tokens[ $i ];
+
+			if ( is_array( $token ) && in_array( $token[0], array( T_WHITESPACE, T_COMMENT, T_DOC_COMMENT ), true ) ) {
+				continue;
+			}
+
+			return $i;
+		}
+
+		return null;
+	}
+
+	/**
+	 * Gets the index of the previous significant token, skipping whitespace and comments.
+	 *
+	 * @since 2.0.0
+	 *
+	 * @param array $tokens Token stream from token_get_all().
+	 * @param int   $index  Index to start scanning backwards from.
+	 * @return int|null The previous significant token index, or null if none exists.
+	 */
+	private function get_previous_significant_token_index( array $tokens, int $index ): ?int {
+		for ( $i = $index - 1; $i >= 0; $i-- ) {
+			$token = $tokens[ $i ];
+
+			if ( is_array( $token ) && in_array( $token[0], array( T_WHITESPACE, T_COMMENT, T_DOC_COMMENT ), true ) ) {
+				continue;
+			}
+
+			return $i;
+		}
+
+		return null;
+	}
+
+	/**
+	 * Removes files under the plugin's top-level tests directory.
+	 *
+	 * The plugin's own test fixtures are not genuine personal data handling and
+	 * should not trigger the check.
+	 *
+	 * @since 2.0.0
+	 *
+	 * @param array  $php_files   List of absolute PHP file paths.
+	 * @param string $plugin_path Absolute path to the plugin directory, with trailing slash.
+	 * @return array Filtered list of absolute PHP file paths.
+	 */
+	private function filter_out_test_paths( array $php_files, string $plugin_path ): array {
+		$root = wp_normalize_path( $plugin_path );
+
+		return array_values(
+			array_filter(
+				$php_files,
+				static function ( string $file ) use ( $root ): bool {
+					$relative = str_replace( $root, '', wp_normalize_path( $file ) );
+
+					// Skip top-level "tests" or "tests/anything" inside the plugin.
+					if ( 0 === strpos( $relative, 'tests' ) && ( strlen( $relative ) === 5 || '/' === $relative[5] ) ) {
+						return false;
+					}
+
+					return true;
+				}
+			)
+		);
+	}
+
+	/**
+	 * Gets the description for the check.
+	 *
+	 * Every check must have a short description explaining what the check does.
+	 *
+	 * @since 2.0.0
+	 *
+	 * @return string Description.
+	 */
+	public function get_description(): string {
+		return __( 'Detects plugins that store personal data without registering a personal data eraser for GDPR compliance.', 'plugin-check' );
+	}
+
+	/**
+	 * Gets the documentation URL for the check.
+	 *
+	 * Every check must have a URL with further information about the check.
+	 *
+	 * @since 2.0.0
+	 *
+	 * @return string The documentation URL.
+	 */
+	public function get_documentation_url(): string {
+		return 'https://developer.wordpress.org/plugins/privacy/adding-the-personal-data-eraser-to-your-plugin/';
+	}
+}
diff --git a/includes/Checker/Default_Check_Repository.php b/includes/Checker/Default_Check_Repository.php
index c22371044..9f97f67c0 100644
--- a/includes/Checker/Default_Check_Repository.php
+++ b/includes/Checker/Default_Check_Repository.php
@@ -101,6 +101,7 @@ private function register_default_checks() {
 				'minified_files'             => new Checks\Plugin_Repo\Minified_Files_Check(),
 				'direct_file_access'         => new Checks\Plugin_Repo\Direct_File_Access_Check(),
 				'external_admin_menu_links'  => new Checks\Plugin_Repo\External_Admin_Menu_Links_Check(),
+				'personal_data_eraser'       => new Checks\Plugin_Repo\Personal_Data_Eraser_Check(),
 				'wp_functions_compatibility' => new Checks\Plugin_Repo\WP_Functions_Compatibility_Check(),
 			)
 		);
diff --git a/tests/phpunit/testdata/plugins/test-plugin-personal-data-eraser-comment-filter/load.php b/tests/phpunit/testdata/plugins/test-plugin-personal-data-eraser-comment-filter/load.php
new file mode 100644
index 000000000..1273ea6fc
--- /dev/null
+++ b/tests/phpunit/testdata/plugins/test-plugin-personal-data-eraser-comment-filter/load.php
@@ -0,0 +1,29 @@
+<?php
+/**
+ * Plugin Name: Test Plugin Personal Data Eraser Comment Filter
+ * Plugin URI: https://github.com/WordPress/plugin-check
+ * Description: Test plugin for the Personal Data Eraser check — stores user meta but only mentions the eraser filter inside a comment.
+ * Requires at least: 6.3
+ * Requires PHP: 7.4
+ * Version: 1.0.0
+ * Author: WordPress Performance Team
+ * Author URI: https://make.wordpress.org/performance/
+ * License: GPLv2 or later
+ * License URI: https://www.gnu.org/licenses/old-licenses/gpl-2.0.html
+ * Text Domain: test-plugin-personal-data-eraser-comment-filter
+ *
+ * @package test-plugin-personal-data-eraser-comment-filter
+ */
+
+/**
+ * Saves a custom preference for a user.
+ *
+ * The plugin should register a data eraser via the
+ * wp_privacy_personal_data_erasers filter, but it never does.
+ *
+ * @param int $user_id User ID.
+ */
+function test_pdel_comment_filter_save_user_preference( $user_id ) {
+	update_user_meta( $user_id, 'test_pdel_comment_filter_preference', 'some_value' );
+}
+add_action( 'user_register', 'test_pdel_comment_filter_save_user_preference' );
diff --git a/tests/phpunit/testdata/plugins/test-plugin-personal-data-eraser-comment-only/load.php b/tests/phpunit/testdata/plugins/test-plugin-personal-data-eraser-comment-only/load.php
new file mode 100644
index 000000000..05a006543
--- /dev/null
+++ b/tests/phpunit/testdata/plugins/test-plugin-personal-data-eraser-comment-only/load.php
@@ -0,0 +1,32 @@
+<?php
+/**
+ * Plugin Name: Test Plugin Personal Data Eraser Comment Only
+ * Plugin URI: https://github.com/WordPress/plugin-check
+ * Description: Test plugin for the Personal Data Eraser check — only mentions personal data function names in comments and strings, never calls them.
+ * Requires at least: 6.3
+ * Requires PHP: 7.4
+ * Version: 1.0.0
+ * Author: WordPress Performance Team
+ * Author URI: https://make.wordpress.org/performance/
+ * License: GPLv2 or later
+ * License URI: https://www.gnu.org/licenses/old-licenses/gpl-2.0.html
+ * Text Domain: test-plugin-personal-data-eraser-comment-only
+ *
+ * @package test-plugin-personal-data-eraser-comment-only
+ */
+
+/**
+ * Notes about potential functions:
+ * update_user_meta() and add_user_meta() are referenced here only inside a
+ * comment and must not be treated as personal data handling.
+ */
+
+/**
+ * Returns an option name that happens to contain a function name as a string.
+ *
+ * @return string Option name.
+ */
+function test_pdel_comment_option() {
+	// Mentioning the call in a comment should not count either: update_user_meta().
+	return 'update_user_meta';
+}
diff --git a/tests/phpunit/testdata/plugins/test-plugin-personal-data-eraser-tests-dir/load.php b/tests/phpunit/testdata/plugins/test-plugin-personal-data-eraser-tests-dir/load.php
new file mode 100644
index 000000000..12fffcdee
--- /dev/null
+++ b/tests/phpunit/testdata/plugins/test-plugin-personal-data-eraser-tests-dir/load.php
@@ -0,0 +1,26 @@
+<?php
+/**
+ * Plugin Name: Test Plugin Personal Data Eraser Tests Directory
+ * Plugin URI: https://github.com/WordPress/plugin-check
+ * Description: Test plugin for the Personal Data Eraser check — stores user meta with the data eraser registered only inside its tests directory.
+ * Requires at least: 6.3
+ * Requires PHP: 7.4
+ * Version: 1.0.0
+ * Author: WordPress Performance Team
+ * Author URI: https://make.wordpress.org/performance/
+ * License: GPLv2 or later
+ * License URI: https://www.gnu.org/licenses/old-licenses/gpl-2.0.html
+ * Text Domain: test-plugin-personal-data-eraser-tests-dir
+ *
+ * @package test-plugin-personal-data-eraser-tests-dir
+ */
+
+/**
+ * Saves a custom preference for a user.
+ *
+ * @param int $user_id User ID.
+ */
+function test_pdel_tests_save_user_preference( $user_id ) {
+	update_user_meta( $user_id, 'test_pdel_tests_preference', 'some_value' );
+}
+add_action( 'user_register', 'test_pdel_tests_save_user_preference' );
diff --git a/tests/phpunit/testdata/plugins/test-plugin-personal-data-eraser-tests-dir/tests/file.php b/tests/phpunit/testdata/plugins/test-plugin-personal-data-eraser-tests-dir/tests/file.php
new file mode 100644
index 000000000..87e7a33c3
--- /dev/null
+++ b/tests/phpunit/testdata/plugins/test-plugin-personal-data-eraser-tests-dir/tests/file.php
@@ -0,0 +1,37 @@
+<?php
+/**
+ * Test fixture that registers a data eraser from within the tests directory.
+ *
+ * @package test-plugin-personal-data-eraser-tests-dir
+ */
+
+/**
+ * Registers the personal data eraser. This lives under tests/ and must not
+ * suppress the missing-erasure warning for the plugin.
+ *
+ * @param array $erasers An array of personal data erasers.
+ * @return array Updated erasers array.
+ */
+function test_pdel_tests_register_eraser( $erasers ) {
+	$erasers['test-pdel-tests'] = array(
+		'eraser_friendly_name' => __( 'Test PDEL Tests Plugin Data', 'test-plugin-personal-data-eraser-tests-dir' ),
+		'callback'             => 'test_pdel_tests_eraser',
+	);
+
+	return $erasers;
+}
+add_filter( 'wp_privacy_personal_data_erasers', 'test_pdel_tests_register_eraser' );
+
+/**
+ * Erases personal data for a user.
+ *
+ * @return array Erasure status array.
+ */
+function test_pdel_tests_eraser() {
+	return array(
+		'items_removed'  => false,
+		'items_retained' => false,
+		'messages'       => array(),
+		'done'           => true,
+	);
+}
diff --git a/tests/phpunit/testdata/plugins/test-plugin-personal-data-eraser-with-errors/load.php b/tests/phpunit/testdata/plugins/test-plugin-personal-data-eraser-with-errors/load.php
new file mode 100644
index 000000000..360e928db
--- /dev/null
+++ b/tests/phpunit/testdata/plugins/test-plugin-personal-data-eraser-with-errors/load.php
@@ -0,0 +1,26 @@
+<?php
+/**
+ * Plugin Name: Test Plugin Personal Data Eraser With Errors
+ * Plugin URI: https://github.com/WordPress/plugin-check
+ * Description: Test plugin for the Personal Data Eraser check — stores user meta but does not register a data eraser.
+ * Requires at least: 6.3
+ * Requires PHP: 7.4
+ * Version: 1.0.0
+ * Author: WordPress Performance Team
+ * Author URI: https://make.wordpress.org/performance/
+ * License: GPLv2 or later
+ * License URI: https://www.gnu.org/licenses/old-licenses/gpl-2.0.html
+ * Text Domain: test-plugin-personal-data-eraser-errors
+ *
+ * @package test-plugin-personal-data-eraser-errors
+ */
+
+/**
+ * Saves a custom preference for a user.
+ *
+ * @param int $user_id User ID.
+ */
+function test_pdel_save_user_preference( $user_id ) {
+	update_user_meta( $user_id, 'test_pdel_preference', 'some_value' );
+}
+add_action( 'user_register', 'test_pdel_save_user_preference' );
diff --git a/tests/phpunit/testdata/plugins/test-plugin-personal-data-eraser-with-wpdb-insert/load.php b/tests/phpunit/testdata/plugins/test-plugin-personal-data-eraser-with-wpdb-insert/load.php
new file mode 100644
index 000000000..b918d532b
--- /dev/null
+++ b/tests/phpunit/testdata/plugins/test-plugin-personal-data-eraser-with-wpdb-insert/load.php
@@ -0,0 +1,36 @@
+<?php
+/**
+ * Plugin Name: Test Plugin Personal Data Eraser With WPDB Insert
+ * Plugin URI: https://github.com/WordPress/plugin-check
+ * Description: Test plugin for the Personal Data Eraser check — writes directly to the database via $wpdb but does not register a data eraser.
+ * Requires at least: 6.3
+ * Requires PHP: 7.4
+ * Version: 1.0.0
+ * Author: WordPress Performance Team
+ * Author URI: https://make.wordpress.org/performance/
+ * License: GPLv2 or later
+ * License URI: https://www.gnu.org/licenses/old-licenses/gpl-2.0.html
+ * Text Domain: test-plugin-personal-data-eraser-wpdb
+ *
+ * @package test-plugin-personal-data-eraser-wpdb
+ */
+
+/**
+ * Saves a custom log entry using a direct database write.
+ *
+ * @param int    $user_id User ID.
+ * @param string $note    Note to store.
+ */
+function test_pdel_wpdb_save_log( $user_id, $note ) {
+	global $wpdb;
+
+	$wpdb->insert(
+		$wpdb->prefix . 'test_pdel_log',
+		array(
+			'user_id' => $user_id,
+			'note'    => $note,
+			'time'    => current_time( 'mysql' ),
+		)
+	);
+}
+add_action( 'user_register', 'test_pdel_wpdb_save_log' );
diff --git a/tests/phpunit/testdata/plugins/test-plugin-personal-data-eraser-without-errors/load.php b/tests/phpunit/testdata/plugins/test-plugin-personal-data-eraser-without-errors/load.php
new file mode 100644
index 000000000..deaa103c5
--- /dev/null
+++ b/tests/phpunit/testdata/plugins/test-plugin-personal-data-eraser-without-errors/load.php
@@ -0,0 +1,69 @@
+<?php
+/**
+ * Plugin Name: Test Plugin Personal Data Eraser Without Errors
+ * Plugin URI: https://github.com/WordPress/plugin-check
+ * Description: Test plugin for the Personal Data Eraser check — stores user meta AND registers a data eraser.
+ * Requires at least: 6.3
+ * Requires PHP: 7.4
+ * Version: 1.0.0
+ * Author: WordPress Performance Team
+ * Author URI: https://make.wordpress.org/performance/
+ * License: GPLv2 or later
+ * License URI: https://www.gnu.org/licenses/old-licenses/gpl-2.0.html
+ * Text Domain: test-plugin-personal-data-eraser-ok
+ *
+ * @package test-plugin-personal-data-eraser-ok
+ */
+
+/**
+ * Saves a custom preference for a user.
+ *
+ * @param int $user_id User ID.
+ */
+function test_pdel_ok_save_user_preference( $user_id ) {
+	update_user_meta( $user_id, 'test_pdel_ok_preference', 'some_value' );
+}
+add_action( 'user_register', 'test_pdel_ok_save_user_preference' );
+
+/**
+ * Registers the personal data eraser.
+ *
+ * @param array $erasers An array of personal data erasers.
+ * @return array Updated erasers array.
+ */
+function test_pdel_ok_register_eraser( $erasers ) {
+	$erasers['test-pdel-ok'] = array(
+		'eraser_friendly_name' => __( 'Test PDEL OK Plugin Data', 'test-plugin-personal-data-eraser-ok' ),
+		'callback'             => 'test_pdel_ok_eraser',
+	);
+	return $erasers;
+}
+add_filter( 'wp_privacy_personal_data_erasers', 'test_pdel_ok_register_eraser' );
+
+/**
+ * Erases personal data for a user.
+ *
+ * @param string $email_address Email address of the user.
+ * @param int    $page          Pagination page number.
+ * @return array Erasure status array.
+ */
+function test_pdel_ok_eraser( $email_address, $page = 1 ) {
+	$user = get_user_by( 'email', $email_address );
+	if ( ! $user ) {
+		return array(
+			'items_removed'  => false,
+			'items_retained' => false,
+			'messages'       => array(),
+			'done'           => true,
+		);
+	}
+
+	$removed = delete_user_meta( $user->ID, 'test_pdel_ok_preference' );
+
+	return array(
+		'items_removed'  => $removed,
+		'items_retained' => false,
+		'messages'       => array(),
+		'done'           => true,
+	);
+}
diff --git a/tests/phpunit/tests/Checker/Checks/Personal_Data_Eraser_Check_Tests.php b/tests/phpunit/tests/Checker/Checks/Personal_Data_Eraser_Check_Tests.php
new file mode 100644
index 000000000..1c3be3d5d
--- /dev/null
+++ b/tests/phpunit/tests/Checker/Checks/Personal_Data_Eraser_Check_Tests.php
@@ -0,0 +1,164 @@
+<?php
+/**
+ * Tests for the Personal_Data_Eraser_Check class.
+ *
+ * @package plugin-check
+ */
+
+use WordPress\Plugin_Check\Checker\Check_Context;
+use WordPress\Plugin_Check\Checker\Check_Result;
+use WordPress\Plugin_Check\Checker\Checks\Plugin_Repo\Personal_Data_Eraser_Check;
+
+class Personal_Data_Eraser_Check_Tests extends WP_UnitTestCase {
+
+	public function test_plugin_with_personal_data_but_no_eraser_triggers_warning() {
+		$check_context = new Check_Context( UNIT_TESTS_PLUGIN_DIR . 'test-plugin-personal-data-eraser-with-errors/load.php' );
+		$check_result  = new Check_Result( $check_context );
+
+		$check = new Personal_Data_Eraser_Check();
+		$check->run( $check_result );
+
+		$warnings = $check_result->get_warnings();
+
+		$this->assertNotEmpty( $warnings );
+
+		$found = false;
+		foreach ( $warnings as $file_warnings ) {
+			foreach ( $file_warnings as $line_warnings ) {
+				foreach ( $line_warnings as $col_warnings ) {
+					foreach ( $col_warnings as $warning ) {
+						if ( isset( $warning['code'] ) && 'missing_personal_data_eraser' === $warning['code'] ) {
+							$found = true;
+							break 4;
+						}
+					}
+				}
+			}
+		}
+
+		$this->assertTrue( $found, 'Expected missing_personal_data_eraser warning was not found.' );
+	}
+
+	public function test_plugin_with_personal_data_and_eraser_has_no_warning() {
+		$check_context = new Check_Context( UNIT_TESTS_PLUGIN_DIR . 'test-plugin-personal-data-eraser-without-errors/load.php' );
+		$check_result  = new Check_Result( $check_context );
+
+		$check = new Personal_Data_Eraser_Check();
+		$check->run( $check_result );
+
+		$found = false;
+		foreach ( $check_result->get_warnings() as $file_warnings ) {
+			foreach ( $file_warnings as $line_warnings ) {
+				foreach ( $line_warnings as $col_warnings ) {
+					foreach ( $col_warnings as $warning ) {
+						if ( isset( $warning['code'] ) && 'missing_personal_data_eraser' === $warning['code'] ) {
+							$found = true;
+							break 4;
+						}
+					}
+				}
+			}
+		}
+
+		$this->assertFalse( $found, 'Unexpected missing_personal_data_eraser warning was found.' );
+	}
+
+	public function test_plugin_with_no_personal_data_has_no_warning() {
+		$check_context = new Check_Context( UNIT_TESTS_PLUGIN_DIR . 'test-plugin-safe-redirect/load.php' );
+		$check_result  = new Check_Result( $check_context );
+
+		$check = new Personal_Data_Eraser_Check();
+		$check->run( $check_result );
+
+		$found = false;
+		foreach ( $check_result->get_warnings() as $file_warnings ) {
+			foreach ( $file_warnings as $line_warnings ) {
+				foreach ( $line_warnings as $col_warnings ) {
+					foreach ( $col_warnings as $warning ) {
+						if ( isset( $warning['code'] ) && 'missing_personal_data_eraser' === $warning['code'] ) {
+							$found = true;
+							break 4;
+						}
+					}
+				}
+			}
+		}
+
+		$this->assertFalse( $found, 'Unexpected missing_personal_data_eraser warning on a plugin with no personal data.' );
+	}
+
+	public function test_plugin_with_wpdb_write_but_no_eraser_triggers_warning() {
+		$check_context = new Check_Context( UNIT_TESTS_PLUGIN_DIR . 'test-plugin-personal-data-eraser-with-wpdb-insert/load.php' );
+		$check_result  = new Check_Result( $check_context );
+
+		$check = new Personal_Data_Eraser_Check();
+		$check->run( $check_result );
+
+		$this->assertTrue(
+			$this->has_warning_code( $check_result, 'missing_personal_data_eraser' ),
+			'Expected missing_personal_data_eraser warning for a $wpdb write was not found.'
+		);
+	}
+
+	public function test_plugin_with_eraser_registered_only_in_tests_directory_triggers_warning() {
+		$check_context = new Check_Context( UNIT_TESTS_PLUGIN_DIR . 'test-plugin-personal-data-eraser-tests-dir/load.php' );
+		$check_result  = new Check_Result( $check_context );
+
+		$check = new Personal_Data_Eraser_Check();
+		$check->run( $check_result );
+
+		$this->assertTrue(
+			$this->has_warning_code( $check_result, 'missing_personal_data_eraser' ),
+			'Expected missing_personal_data_eraser warning despite an eraser registered under the tests directory.'
+		);
+	}
+
+	public function test_plugin_with_personal_data_only_in_comments_and_strings_has_no_warning() {
+		$check_context = new Check_Context( UNIT_TESTS_PLUGIN_DIR . 'test-plugin-personal-data-eraser-comment-only/load.php' );
+		$check_result  = new Check_Result( $check_context );
+
+		$check = new Personal_Data_Eraser_Check();
+		$check->run( $check_result );
+
+		$this->assertFalse(
+			$this->has_warning_code( $check_result, 'missing_personal_data_eraser' ),
+			'Unexpected missing_personal_data_eraser warning when personal data appears only in comments and strings.'
+		);
+	}
+
+	public function test_plugin_mentioning_eraser_filter_only_in_comment_triggers_warning() {
+		$check_context = new Check_Context( UNIT_TESTS_PLUGIN_DIR . 'test-plugin-personal-data-eraser-comment-filter/load.php' );
+		$check_result  = new Check_Result( $check_context );
+
+		$check = new Personal_Data_Eraser_Check();
+		$check->run( $check_result );
+
+		$this->assertTrue(
+			$this->has_warning_code( $check_result, 'missing_personal_data_eraser' ),
+			'Expected missing_personal_data_eraser warning when the eraser filter is only mentioned in a comment.'
+		);
+	}
+
+	/**
+	 * Checks whether the given result contains a warning with the given code.
+	 *
+	 * @param Check_Result $result The check result to inspect.
+	 * @param string       $code   The warning code to look for.
+	 * @return bool True if a matching warning exists, false otherwise.
+	 */
+	private function has_warning_code( Check_Result $result, string $code ): bool {
+		foreach ( $result->get_warnings() as $file_warnings ) {
+			foreach ( $file_warnings as $line_warnings ) {
+				foreach ( $line_warnings as $col_warnings ) {
+					foreach ( $col_warnings as $warning ) {
+						if ( isset( $warning['code'] ) && $code === $warning['code'] ) {
+							return true;
+						}
+					}
+				}
+			}
+		}
+
+		return false;
+	}
+}