Reduce responsibility of Lily\Middleware\Session\*Store

By simplifying the responsibility of session stores and moving logic to
session middleware we can keep behaviour consistent in one place rather
than in each store.

src/Lily/Middleware/Session.php

@@ -32,7 +32,13 @@ public function __invoke($handler)
         return function ($request) use ($handler, $store) {
             $request = $store->get($request);
             $response = $handler($request);
-            $response = $store->set($request, $response);
+
+            if (empty($response['session'])) {
+                $response['session'] = array();
+            }
+
+            $response['session'] += $request['session'];
+            $response = $store->set($response);
             return $response;
         };
     }

src/Lily/Middleware/Session/CookieStore.php

@@ -39,16 +39,10 @@ public function get($request)
         return $request;
     }
 
-    public function set($request, $response)
+    public function set($response)
     {
         if (isset($response['session'])) {
-            $session = $response['session'];
-
-            if (isset($request['session'])) {
-                $session += $request['session'];
-            }
-
-            $value = json_encode($session);
+            $value = json_encode($response['session']);
             $response['cookies'][$this->name] = compact('value') + $this->cookie;
         }
 

src/Lily/Middleware/Session/NativeStore.php

@@ -25,10 +25,10 @@ public function get($request)
         return $request;
     }
 
-    public function set($request, $response)
+    public function set($response)
     {
         if (isset($response['session'])) {
-            $_SESSION = $response['session'] + $_SESSION;
+            $_SESSION = $response['session'];
         }
 
         return $response;

test/Lily/Mock/MockSessionStore.php

@@ -16,10 +16,10 @@ class MockSessionStore
 {
     public $session = array();
 
-    public function set($request, $response)
+    public function set($response)
     {
         if (isset($response['session'])) {
-            $this->session = $response['session'] + $this->session;
+            $this->session = $response['session'];
         }
 
         return $response;

test/Lily/Test/Middleware/Session/SessionStoreTest.php

@@ -12,46 +12,20 @@
 
 abstract class SessionStoreTest extends \PHPUnit_Framework_TestCase
 {
-    public function testItShouldAddArrayToSession()
+    public function testItShouldUseArrayAsSession()
     {
         $expectedValue = 'some value';
-        $response = $this->store()->set(array(), array(
+        $response = $this->store()->set(array(
             'session' => array('a' => $expectedValue),
         ));
         $this->assertSame($expectedValue, $this->getFromStore($response, 'a'));
     }
 
-    public function testItShouldOverwriteArrayKeyInSession()
-    {
-        $expectedValue = 'overwritten value';
-        $request = $this->addToStore('b', 'initial value');
-        $response = $this->store()->set($request, array(
-            'session' => array('b' => $expectedValue),
-        ));
-        $this->assertSame($expectedValue, $this->getFromStore($response, 'b'));
-    }
-
-    public function testItShouldNotOverwriteOtherKeys()
-    {
-        $expectedValue = 'other key value';
-        $request = $this->addToStore('a', $expectedValue);
-        $response = $this->store()->set($request, array(
-            'session' => array('b' => 'unrelated'),
-        ));
-        $this->assertSame($expectedValue, $this->getFromStore($response, 'a'));
-    }
-
     public function testItShouldGetArrayFromSession()
     {
         $expectedValue = 'something';
         $request = $this->addToStore('c', $expectedValue);
         $request = $this->store()->get($request);
         $this->assertSame($expectedValue, $request['session']['c']);
     }
-
-    public function testItShouldAlwaysAddSessionKey()
-    {
-        $request = $this->store()->get(array());
-        $this->assertArrayHasKey('session', $request);
-    }
 }