đã tạo được test case của createUser

vendor/php-webdriver/webdriver/lib/WebDriverCommandExecutor.php

@@ -0,0 +1,17 @@
+<?php
+
+namespace Facebook\WebDriver;
+
+use Facebook\WebDriver\Remote\WebDriverCommand;
+use Facebook\WebDriver\Remote\WebDriverResponse;
+
+/**
+ * Interface for all command executor.
+ */
+interface WebDriverCommandExecutor
+{
+    /**
+     * @return WebDriverResponse
+     */
+    public function execute(WebDriverCommand $command);
+}