Added tests covering the 2 ways to instantiate the driver

tests/Behat/Mink/Driver/ExtraDriverTest.php

@@ -0,0 +1,30 @@
+<?php
+
+namespace Tests\Behat\Mink\Driver;
+
+use Behat\Mink\Driver\GoutteDriver;
+
+/**
+ * @group unit
+ */
+class ExtraDriverTest extends \PHPUnit_Framework_TestCase
+{
+    public function testInstantiateWithClient()
+    {
+        $client = $this->getMockBuilder('Behat\Mink\Driver\Goutte\Client')->disableOriginalConstructor()->getMock();
+        $client->expects($this->once())
+            ->method('followRedirects')
+            ->with(true);
+
+        $driver = new GoutteDriver($client);
+
+        $this->assertSame($client, $driver->getClient());
+    }
+
+    public function testInstantiateWithoutClient()
+    {
+        $driver = new GoutteDriver();
+
+        $this->assertInstanceOf('Behat\Mink\Driver\Goutte\Client', $driver->getClient());
+    }
+}

tests/Behat/Mink/Driver/GoutteDriverTest.php

@@ -5,7 +5,7 @@
 use Behat\Mink\Driver\GoutteDriver;
 
 /**
- * @group gouttedriver
+ * @group functional
  */
 class GoutteDriverTest extends GeneralDriverTest
 {