Added specs for the classes

spec/Behat/MinkExtension/ExtensionSpec.php

@@ -0,0 +1,18 @@
+<?php
+
+namespace spec\Behat\MinkExtension;
+
+use PhpSpec\ObjectBehavior;
+
+class ExtensionSpec extends ObjectBehavior
+{
+    function it_is_a_testwork_extension()
+    {
+        $this->shouldHaveType('Behat\Testwork\ServiceContainer\Extension');
+    }
+
+    function it_is_named_mink()
+    {
+        $this->getConfigKey()->shouldReturn('mink');
+    }
+}