diff --git a/src/Factory/ResultRendererFactory.php b/src/Factory/ResultRendererFactory.php
index 4ff99896..22ec4798 100644
--- a/src/Factory/ResultRendererFactory.php
+++ b/src/Factory/ResultRendererFactory.php
@@ -37,11 +37,11 @@ class ResultRendererFactory
      */
     public function registerRenderer($resultClass, $rendererClass)
     {
-        if (!class_implements($resultClass, ResultInterface::class)) {
+        if (!$this->isImplementationNameOfClass($resultClass, ResultInterface::class)) {
             throw new InvalidArgumentException;
         }
 
-        if (!class_implements($rendererClass, ResultRendererInterface::class)) {
+        if (!$this->isImplementationNameOfClass($rendererClass, ResultRendererInterface::class)) {
             throw new InvalidArgumentException;
         }
 
@@ -61,4 +61,9 @@ public function create(ResultInterface $result)
 
         return new $this->mappings[$class]($result);
     }
+
+    protected function isImplementationNameOfClass($implementationName, $className)
+    {
+        return is_string($implementationName) && is_subclass_of($implementationName, $className);
+    }
 }
diff --git a/test/Asset/PatchableExercise.php b/test/Asset/PatchableExercise.php
index ba0b9913..e638cb7e 100644
--- a/test/Asset/PatchableExercise.php
+++ b/test/Asset/PatchableExercise.php
@@ -54,7 +54,7 @@ public function getProblem()
      */
     public function tearDown()
     {
-        
+        // TODO: Implement tearDown() method.
     }
 
     /**
diff --git a/test/Check/ComposerCheckTest.php b/test/Check/ComposerCheckTest.php
index 4dcabdd3..f62642a7 100644
--- a/test/Check/ComposerCheckTest.php
+++ b/test/Check/ComposerCheckTest.php
@@ -40,7 +40,6 @@ public function setUp()
 
         $this->assertTrue($this->check->canRun(ExerciseType::CGI()));
         $this->assertTrue($this->check->canRun(ExerciseType::CLI()));
-
     }
     
     public function testExceptionIsThrownIfNotValidExercise()
diff --git a/test/Factory/ResultRendererFactoryTest.php b/test/Factory/ResultRendererFactoryTest.php
new file mode 100644
index 00000000..51cb9c47
--- /dev/null
+++ b/test/Factory/ResultRendererFactoryTest.php
@@ -0,0 +1,90 @@
+<?php
+
+namespace PhpSchool\PhpWorkshopTest\Factory;
+
+use PhpSchool\PhpWorkshop\Exception\InvalidArgumentException;
+use PhpSchool\PhpWorkshop\Factory\ResultRendererFactory;
+use PhpSchool\PhpWorkshop\ResultRenderer\ResultRendererInterface;
+use PhpSchool\PhpWorkshop\Result\ResultInterface;
+use PHPUnit_Framework_TestCase;
+use RuntimeException;
+
+/**
+ * Class ResultsRendererFactoryTest
+ * @package PhpSchool\PhpWorkshopTest\Factory
+ * @author Aydin Hassan <aydin@hotmail.co.uk>
+ */
+class ResultsRendererFactoryTest extends PHPUnit_Framework_TestCase
+{
+    /**
+     * @expectedException InvalidArgumentException
+     */
+    public function testRegisterRendererRequiresResultInterface()
+    {
+        $resultClass = get_class($this->createMock(PHPUnit_Framework_TestCase::class));
+        $rendererClass = get_class($this->createMock(ResultRendererInterface::class));
+        $factory = new ResultRendererFactory();
+        
+        $factory->registerRenderer($resultClass, $rendererClass);
+    }
+
+    /**
+     * @expectedException InvalidArgumentException
+     */
+    public function testRegisterRendererRequiresResultRendererInterface()
+    {
+        $resultClass = get_class($this->createMock(ResultInterface::class));
+        $rendererClass = get_class($this->createMock(PHPUnit_Framework_TestCase::class));
+        $factory = new ResultRendererFactory();
+        
+        $factory->registerRenderer($resultClass, $rendererClass);
+    }
+
+    /**
+     * @expectedException InvalidArgumentException
+     */
+    public function testRegisterRendererRequiresResultClassToBeString()
+    {
+        $resultClass = $this->createMock(ResultInterface::class);
+        $rendererClass = get_class($this->createMock(ResultRendererInterface::class));
+        $factory = new ResultRendererFactory();
+        
+        $factory->registerRenderer($resultClass, $rendererClass);
+    }
+
+    /**
+     * @expectedException InvalidArgumentException
+     */
+    public function testRegisterRendererRequiresRendererClassToBeString()
+    {
+        $resultClass = get_class($this->createMock(ResultInterface::class));
+        $rendererClass = $this->createMock(ResultRendererInterface::class);
+        $factory = new ResultRendererFactory();
+        
+        $factory->registerRenderer($resultClass, $rendererClass);
+    }
+
+    /**
+     * @expectedException RuntimeException
+     */
+    public function testCreateRequiresMappingToClassName()
+    {
+        $resultClass = $this->createMock(ResultInterface::class);
+        $factory = new ResultRendererFactory();
+
+        $factory->create($resultClass);
+    }
+
+    public function testCreateReturnsMappedRendererInterface()
+    {
+        $resultClass = $this->createMock(ResultInterface::class);
+        $resultClassName = get_class($resultClass);
+        $rendererClassName = get_class($this->createMock(ResultRendererInterface::class));
+        $factory = new ResultRendererFactory();
+        $factory->registerRenderer($resultClassName, $rendererClassName);
+
+        $returnedRenderer = $factory->create($resultClass);
+
+        $this->assertInstanceOf($rendererClassName, $returnedRenderer);
+    }
+}