diff --git a/tests/phpunit/tests/admin/includes/misc/wpRefreshPostLock.php b/tests/phpunit/tests/admin/includes/misc/wpRefreshPostLock.php
new file mode 100644
index 0000000000000..2814ffae2d838
--- /dev/null
+++ b/tests/phpunit/tests/admin/includes/misc/wpRefreshPostLock.php
@@ -0,0 +1,208 @@
+<?php
+/**
+ * Test wp_refresh_post_lock().
+ *
+ * @group admin
+ * @group misc
+ *
+ * @covers ::wp_refresh_post_lock
+ */
+class Tests_Admin_Includes_Misc_WpRefreshPostLock extends WP_UnitTestCase {
+
+	/**
+	 * Post ID.
+	 *
+	 * @var int
+	 */
+	protected static $post_id;
+
+	/**
+	 * User ID.
+	 *
+	 * @var int
+	 */
+	protected static $user_id;
+
+	/**
+	 * Other user ID.
+	 *
+	 * @var int
+	 */
+	protected static $other_user_id;
+
+	/**
+	 * Set up before class.
+	 */
+	public static function wpSetUpBeforeClass( WP_UnitTest_Factory $factory ) {
+		self::$user_id       = $factory->user->create( array( 'role' => 'editor' ) );
+		self::$other_user_id = $factory->user->create( array( 'role' => 'editor' ) );
+		self::$post_id       = $factory->post->create( array( 'post_author' => self::$user_id ) );
+	}
+
+	/**
+	 * Tests wp_refresh_post_lock() with missing data.
+	 *
+	 * @ticket 65196
+	 */
+	public function test_wp_refresh_post_lock_missing_data() {
+		$response = array( 'existing' => 'data' );
+		$data     = array();
+
+		$result = wp_refresh_post_lock( $response, $data, 'edit-post' );
+
+		$this->assertSame( $response, $result, 'Response should remain unchanged if wp-refresh-post-lock is missing.' );
+	}
+
+	/**
+	 * Tests wp_refresh_post_lock() with invalid post ID.
+	 *
+	 * @ticket 65196
+	 *
+	 * @dataProvider data_wp_refresh_post_lock_invalid_post_id
+	 *
+	 * @param mixed $post_id Invalid post ID.
+	 *
+	 * @return array<string, array{post_id: mixed}>
+	 */
+	public function test_wp_refresh_post_lock_invalid_post_id( $post_id ) {
+		wp_set_current_user( self::$user_id );
+
+		$response = array();
+		$data     = array(
+			'wp-refresh-post-lock' => array(
+				'post_id' => $post_id,
+			),
+		);
+
+		$result = wp_refresh_post_lock( $response, $data, 'edit-post' );
+
+		$this->assertSame( $response, $result, 'Response should remain unchanged with invalid post ID.' );
+	}
+
+	/**
+	 * Data provider for test_wp_refresh_post_lock_invalid_post_id.
+	 *
+	 * @return array<string, array{post_id: mixed}>
+	 */
+	public function data_wp_refresh_post_lock_invalid_post_id(): array {
+		return array(
+			'zero'     => array( 0 ),
+			'string'   => array( 'abc' ),
+			'negative' => array( -1 ),
+		);
+	}
+
+	/**
+	 * Tests wp_refresh_post_lock() when user cannot edit the post.
+	 *
+	 * @ticket 65196
+	 */
+	public function test_wp_refresh_post_lock_no_permission() {
+		$subscriber_id = self::factory()->user->create( array( 'role' => 'subscriber' ) );
+		wp_set_current_user( $subscriber_id );
+
+		$response = array();
+		$data     = array(
+			'wp-refresh-post-lock' => array(
+				'post_id' => self::$post_id,
+			),
+		);
+
+		$result = wp_refresh_post_lock( $response, $data, 'edit-post' );
+
+		$this->assertSame( $response, $result, 'Response should remain unchanged if user cannot edit the post.' );
+	}
+
+	/**
+	 * Tests wp_refresh_post_lock() when post is locked by another user.
+	 *
+	 * @ticket 65196
+	 *
+	 * @dataProvider data_wp_refresh_post_lock_by_another_user
+	 *
+	 * @param bool $show_avatars Whether to show avatars.
+	 *
+	 * @return array<string, array{show_avatars: bool}>
+	 */
+	public function test_wp_refresh_post_lock_by_another_user( $show_avatars ) {
+		wp_set_current_user( self::$user_id );
+		update_option( 'show_avatars', $show_avatars );
+
+		// Lock post by another user.
+		$now  = time();
+		$lock = "$now:" . self::$other_user_id;
+		update_post_meta( self::$post_id, '_edit_lock', $lock );
+
+		$response = array();
+		$data     = array(
+			'wp-refresh-post-lock' => array(
+				'post_id' => self::$post_id,
+			),
+		);
+
+		$result = wp_refresh_post_lock( $response, $data, 'edit-post' );
+
+		$this->assertArrayHasKey( 'wp-refresh-post-lock', $result );
+		$this->assertArrayHasKey( 'lock_error', $result['wp-refresh-post-lock'] );
+
+		$error      = $result['wp-refresh-post-lock']['lock_error'];
+		$other_user = get_userdata( self::$other_user_id );
+
+		$this->assertSame( $other_user->display_name, $error['name'] );
+		$this->assertStringContainsString( $other_user->display_name, $error['text'] );
+
+		if ( $show_avatars ) {
+			$this->assertArrayHasKey( 'avatar_src', $error );
+			$this->assertArrayHasKey( 'avatar_src_2x', $error );
+		} else {
+			$this->assertArrayNotHasKey( 'avatar_src', $error );
+			$this->assertArrayNotHasKey( 'avatar_src_2x', $error );
+		}
+
+		// Cleanup.
+		delete_post_meta( self::$post_id, '_edit_lock' );
+	}
+
+	/**
+	 * Data provider for test_wp_refresh_post_lock_by_another_user.
+	 *
+	 * @return array<string, array{show_avatars: bool}>
+	 */
+	public function data_wp_refresh_post_lock_by_another_user(): array {
+		return array(
+			'avatars enabled'  => array( true ),
+			'avatars disabled' => array( false ),
+		);
+	}
+
+	/**
+	 * Tests wp_refresh_post_lock() when post is not locked or locked by the same user.
+	 *
+	 * @ticket 65196
+	 */
+	public function test_wp_refresh_post_lock_success() {
+		wp_set_current_user( self::$user_id );
+
+		// Ensure no lock.
+		delete_post_meta( self::$post_id, '_edit_lock' );
+
+		$response = array();
+		$data     = array(
+			'wp-refresh-post-lock' => array(
+				'post_id' => self::$post_id,
+			),
+		);
+
+		$result = wp_refresh_post_lock( $response, $data, 'edit-post' );
+
+		$this->assertArrayHasKey( 'wp-refresh-post-lock', $result );
+		$this->assertArrayHasKey( 'new_lock', $result['wp-refresh-post-lock'] );
+
+		$new_lock = $result['wp-refresh-post-lock']['new_lock'];
+		$this->assertStringContainsString( (string) self::$user_id, $new_lock );
+
+		// Verify meta was updated.
+		$meta_lock = get_post_meta( self::$post_id, '_edit_lock', true );
+		$this->assertSame( $new_lock, $meta_lock );
+	}
+}