diff --git a/Behavioral/Observer/Tests/ObserverTest.php b/Behavioral/Observer/Tests/ObserverTest.php
index d9dacec..6a3f369 100644
--- a/Behavioral/Observer/Tests/ObserverTest.php
+++ b/Behavioral/Observer/Tests/ObserverTest.php
@@ -57,7 +57,7 @@ class ObserverTest extends \PHPUnit_Framework_TestCase
     public function testUpdateCalling()
     {
         $subject = new User();
-        $observer = $this->getMock('SplObserver');
+        $observer = $this->createMock('SplObserver');
         $subject->attach($observer);
 
         $observer->expects($this->once())
diff --git a/Makefile b/Makefile
index 52169e6..c3841a2 100644
--- a/Makefile
+++ b/Makefile
@@ -190,3 +190,20 @@ pseudoxml:
 	$(SPHINXBUILD) -b pseudoxml $(ALLSPHINXOPTS) $(BUILDDIR)/pseudoxml
 	@echo
 	@echo "Build finished. The pseudo-XML files are in $(BUILDDIR)/pseudoxml."
+
+composer.phar:
+	php -r "copy('https://getcomposer.org/installer', 'composer-setup.php');"
+	php -r "if (hash_file('SHA384', 'composer-setup.php') === 'e115a8dc7871f15d853148a7fbac7da27d6c0030b848d9b3dc09e2a0388afed865e6a3d6b3c0fad45c48e2b5fc1196ae') { echo 'Installer verified'; } else { echo 'Installer corrupt'; unlink('composer-setup.php'); } echo PHP_EOL;"
+	php composer-setup.php
+	php -r "unlink('composer-setup.php');"
+
+install: vendor
+
+vendor: composer.phar
+	php composer.phar install
+
+cs: install
+	./vendor/bin/phpcs -p --standard=PSR2 --ignore=vendor .
+
+test: install cs
+	./vendor/bin/phpunit
diff --git a/Structural/Decorator/Tests/DecoratorTest.php b/Structural/Decorator/Tests/DecoratorTest.php
index 689caf2..2878772 100644
--- a/Structural/Decorator/Tests/DecoratorTest.php
+++ b/Structural/Decorator/Tests/DecoratorTest.php
@@ -73,7 +73,7 @@ class DecoratorTest extends \PHPUnit_Framework_TestCase
      */
     public function testDecoratorOnlyAcceptRenderer()
     {
-        $mock = $this->getMock('DesignPatterns\Structural\Decorator\RendererInterface');
+        $mock = $this->createMock('DesignPatterns\Structural\Decorator\RendererInterface');
         $dec = $this->getMockForAbstractClass('DesignPatterns\Structural\Decorator\Decorator', array($mock));
         $this->assertNotNull($dec);
     }
diff --git a/Structural/Proxy/Record.php b/Structural/Proxy/Record.php
index 7ae4a3c..fd9bb0c 100644
--- a/Structural/Proxy/Record.php
+++ b/Structural/Proxy/Record.php
@@ -8,44 +8,44 @@ namespace DesignPatterns\Structural\Proxy;
 class Record
 {
     /**
-     * @var array|null
+     * @var string[]
      */
-    protected $data;
+    private $data;
 
     /**
-     * @param null $data
+     * @param string[] $data
      */
-    public function __construct($data = null)
+    public function __construct(array $data = [])
     {
-        $this->data = (array) $data;
+        $this->data = $data;
     }
 
     /**
-     * magic setter.
+     * magic setter
      *
      * @param string $name
      * @param mixed  $value
      *
      * @return void
      */
-    public function __set($name, $value)
+    public function __set(string $name, string $value)
     {
-        $this->data[(string) $name] = $value;
+        $this->data[$name] = $value;
     }
 
     /**
-     * magic getter.
+     * magic getter
      *
      * @param string $name
      *
-     * @return mixed|null
+     * @return string|null
      */
-    public function __get($name)
+    public function __get(string $name): string
     {
-        if (array_key_exists($name, $this->data)) {
-            return $this->data[(string) $name];
+        if (isset($this->data[$name])) {
+            return $this->data[$name];
         } else {
-            return;
+            return null;
         }
     }
 }
diff --git a/Structural/Proxy/RecordProxy.php b/Structural/Proxy/RecordProxy.php
index f8c78a8..2432e01 100644
--- a/Structural/Proxy/RecordProxy.php
+++ b/Structural/Proxy/RecordProxy.php
@@ -2,25 +2,22 @@
 
 namespace DesignPatterns\Structural\Proxy;
 
-/**
- * Class RecordProxy.
- */
 class RecordProxy extends Record
 {
     /**
      * @var bool
      */
-    protected $isDirty = false;
+    private $isDirty = false;
 
     /**
      * @var bool
      */
-    protected $isInitialized = false;
+    private $isInitialized = false;
 
     /**
      * @param array $data
      */
-    public function __construct($data)
+    public function __construct(array $data)
     {
         parent::__construct($data);
 
@@ -28,23 +25,30 @@ class RecordProxy extends Record
         // since Record will hold our business logic, we don't want to
         // implement this behaviour there, but instead in a new proxy class
         // that extends the Record class
-        if (null !== $data) {
+        if (count($data) > 0) {
             $this->isInitialized = true;
             $this->isDirty = true;
         }
     }
 
     /**
-     * magic setter.
+     * magic setter
      *
      * @param string $name
-     * @param mixed  $value
-     *
-     * @return void
+     * @param string  $value
      */
-    public function __set($name, $value)
+    public function __set(string $name, string $value)
     {
         $this->isDirty = true;
+
         parent::__set($name, $value);
     }
+
+    /**
+     * @return bool
+     */
+    public function isDirty(): bool
+    {
+        return $this->isDirty;
+    }
 }
diff --git a/Structural/Proxy/Tests/ProxyTest.php b/Structural/Proxy/Tests/ProxyTest.php
new file mode 100644
index 0000000..955282f
--- /dev/null
+++ b/Structural/Proxy/Tests/ProxyTest.php
@@ -0,0 +1,25 @@
+<?php
+
+namespace DesignPatterns\Structural\Proxy\Tests;
+
+use DesignPatterns\Structural\Decorator;
+use DesignPatterns\Structural\Proxy\RecordProxy;
+
+class ProxyTest extends \PHPUnit_Framework_TestCase
+{
+    public function testWillSetDirtyFlagInProxy()
+    {
+        $recordProxy = new RecordProxy([]);
+        $recordProxy->foobar = 'baz';
+
+        $this->assertTrue($recordProxy->isDirty());
+    }
+
+    public function testProxyIsInstanceOfRecord()
+    {
+        $recordProxy = new RecordProxy([]);
+        $recordProxy->foobar = 'baz';
+
+        $this->assertInstanceOf('DesignPatterns\Structural\Proxy\Record', $recordProxy);
+    }
+}