feat: add json file transport

tests/bootstrap.php

@@ -143,11 +143,12 @@ if ( ! function_exists( 'wp_json_encode' ) ) {
 	 * Minimal JSON encoder for unit tests.
 	 *
 	 * @param mixed $value Value to encode.
+	 * @param int   $flags JSON encoding flags.
 	 * @return string|false
 	 */
-	function wp_json_encode( $value ) {
+	function wp_json_encode( $value, $flags = 0 ) {
 		// phpcs:ignore -- Test stub for WordPress' wp_json_encode().
-		return json_encode( $value );
+		return json_encode( $value, $flags );
 	}
 }