Update or fix tests

The test for removing redundant leading slashes is likely redundant itself.
It checks that something that does not require escaping is not escaped.

tests/phpunit/tests/blocks/editor.php

@@ -630,13 +630,13 @@ function filter_add_preload_paths( $preload_paths, WP_Block_Editor_Context $cont
 
 		$after = implode( '', wp_scripts()->registered['wp-api-fetch']->extra['after'] );
 		$this->assertStringContainsString( 'wp.apiFetch.createPreloadingMiddleware', $after );
-		$this->assertStringContainsString( '"\/wp\/v2\/blocks"', $after );
-		$this->assertStringContainsString( '"\/wp\/v2\/types"', $after );
+		$this->assertStringContainsString( '"/wp/v2/blocks"', $after );
+		$this->assertStringContainsString( '"/wp/v2/types"', $after );
 	}
 
 	/**
 	 * @ticket 54558
-	 * @dataProvider data_block_editor_rest_api_preload_adds_missing_leading_slash
+	 * @dataProvider data_block_editor_rest_api_preload_does_not_add_redundant_leading_slash
 	 *
 	 * @covers ::block_editor_rest_api_preload
 	 *
@@ -692,31 +692,31 @@ public function test_get_classic_theme_supports_block_editor_settings() {
 	 *
 	 * @return array
 	 */
-	public function data_block_editor_rest_api_preload_adds_missing_leading_slash() {
+	public function data_block_editor_rest_api_preload_does_not_add_redundant_leading_slash() {
 		return array(
 			'a string without a slash'               => array(
 				'preload_paths' => array( 'wp/v2/blocks' ),
-				'expected'      => '\/wp\/v2\/blocks',
+				'expected'      => '/wp/v2/blocks',
 			),
 			'a string with a slash'                  => array(
 				'preload_paths' => array( '/wp/v2/blocks' ),
-				'expected'      => '\/wp\/v2\/blocks',
+				'expected'      => '/wp/v2/blocks',
 			),
 			'a string starting with a question mark' => array(
 				'preload_paths' => array( '?context=edit' ),
 				'expected'      => '/?context=edit',
 			),
 			'an array with a string without a slash' => array(
 				'preload_paths' => array( array( 'wp/v2/blocks', 'OPTIONS' ) ),
-				'expected'      => '\/wp\/v2\/blocks',
+				'expected'      => '/wp/v2/blocks',
 			),
 			'an array with a string with a slash'    => array(
 				'preload_paths' => array( array( '/wp/v2/blocks', 'OPTIONS' ) ),
-				'expected'      => '\/wp\/v2\/blocks',
+				'expected'      => '/wp/v2/blocks',
 			),
 			'an array with a string starting with a question mark' => array(
 				'preload_paths' => array( array( '?context=edit', 'OPTIONS' ) ),
-				'expected'      => '\/?context=edit',
+				'expected'      => '/?context=edit',
 			),
 		);
 	}