diff --git a/composer.json b/composer.json
index 48a8c4f..122e2d2 100644
--- a/composer.json
+++ b/composer.json
@@ -28,7 +28,8 @@
         "symfony/expression-language": "^2.7"
     },
     "require-dev": {
-        "phpunit/phpunit": "4.8.*"
+        "phpunit/phpunit": "4.8.*",
+        "mikey179/vfsStream": "^1.0"
     },
     "bin": ["bin/deprecation-detector"],
     "autoload": {
diff --git a/composer.lock b/composer.lock
index 47f7c65..3124a7c 100644
--- a/composer.lock
+++ b/composer.lock
@@ -4,9 +4,55 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#composer-lock-the-lock-file",
         "This file is @generated automatically"
     ],
-    "hash": "9e6c3b0f18e1265f8887eac427da82fc",
-    "content-hash": "13a91fb9ffa68f2ba28c400a08e6baed",
+    "hash": "2fd97b5f4aab66649dd2d818e5d51a5b",
+    "content-hash": "6e15ef62add11bbfee0cbe056d7f67f0",
     "packages": [
+        {
+            "name": "mikey179/vfsStream",
+            "version": "v1.6.0",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/mikey179/vfsStream.git",
+                "reference": "73bcb605b741a7d5044b47592338c633788b0eb7"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/mikey179/vfsStream/zipball/73bcb605b741a7d5044b47592338c633788b0eb7",
+                "reference": "73bcb605b741a7d5044b47592338c633788b0eb7",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.3.0"
+            },
+            "require-dev": {
+                "phpunit/phpunit": "~4.5"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "1.6.x-dev"
+                }
+            },
+            "autoload": {
+                "psr-0": {
+                    "org\\bovigo\\vfs\\": "src/main/php"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "BSD-3-Clause"
+            ],
+            "authors": [
+                {
+                    "name": "Frank Kleine",
+                    "homepage": "http://frankkleine.de/",
+                    "role": "Developer"
+                }
+            ],
+            "description": "Virtual file system to mock the real file system in unit tests.",
+            "homepage": "http://vfs.bovigo.org/",
+            "time": "2015-10-06 16:59:57"
+        },
         {
             "name": "nikic/php-parser",
             "version": "v1.4.1",
diff --git a/tests/RuleSet/Loader/DirectoryLoaderTest.php b/tests/RuleSet/Loader/DirectoryLoaderTest.php
new file mode 100644
index 0000000..7a26295
--- /dev/null
+++ b/tests/RuleSet/Loader/DirectoryLoaderTest.php
@@ -0,0 +1,52 @@
+<?php
+
+namespace SensioLabs\DeprecationDetector\Tests\RuleSet\Loader;
+
+use Prophecy\Argument;
+use SensioLabs\DeprecationDetector\RuleSet\Loader\DirectoryLoader;
+use SensioLabs\DeprecationDetector\RuleSet\RuleSet;
+
+class DirectoryLoaderTest extends \PHPUnit_Framework_TestCase
+{
+    public function testClassIsInitializable()
+    {
+        $traverser = $this->prophesize('\SensioLabs\DeprecationDetector\RuleSet\Traverser');
+        $cache = $this->prophesize('\SensioLabs\DeprecationDetector\RuleSet\Cache');
+
+        $loader = new DirectoryLoader($traverser->reveal(), $cache->reveal());
+
+        $this->assertInstanceOf('\SensioLabs\DeprecationDetector\RuleSet\Loader\DirectoryLoader', $loader);
+    }
+
+    public function testLoadRuleSetUncached()
+    {
+        $traverser = $this->prophesize('\SensioLabs\DeprecationDetector\RuleSet\Traverser');
+        $traverser->traverse(Argument::any())
+            ->willReturn(new RuleSet());
+
+        $cache = $this->prophesize('\SensioLabs\DeprecationDetector\RuleSet\Cache');
+
+        $loader = new DirectoryLoader($traverser->reveal(), $cache->reveal());
+
+        $actualRuleSet = $loader->loadRuleSet('any');
+
+        $this->assertInstanceOf('\SensioLabs\DeprecationDetector\RuleSet\RuleSet', $actualRuleSet);
+    }
+
+    public function testLoadRuleSetCached()
+    {
+        $traverser = $this->prophesize('\SensioLabs\DeprecationDetector\RuleSet\Traverser');
+
+        $cache = $this->prophesize('\SensioLabs\DeprecationDetector\RuleSet\Cache');
+        $cache->has(Argument::any())
+            ->willReturn(true);
+        $cache->getCachedRuleSet(Argument::any())
+            ->willReturn(new RuleSet());
+
+        $loader = new DirectoryLoader($traverser->reveal(), $cache->reveal());
+
+        $actualRuleSet = $loader->loadRuleSet('any');
+
+        $this->assertInstanceOf('\SensioLabs\DeprecationDetector\RuleSet\RuleSet', $actualRuleSet);
+    }
+}