minor #10326 [HttpFoundation][Tests] Add tests for RequestStack class (inalgnu)

This PR was submitted for the 2.3-dev branch but it was merged into the 2.3 branch instead (closes #10326).

Discussion
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[HttpFoundation][Tests] Add tests for RequestStack class

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | n/a
| License       | MIT
| Doc PR        | n/a

Commits
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6f25d39 [HttpFoundation][Tests] Add tests for RequestStack class

src/Symfony/Component/HttpFoundation/Tests/RequestStackTest.php

@@ -0,0 +1,69 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\HttpFoundation\Tests;
+
+use Symfony\Component\HttpFoundation\Request;
+use Symfony\Component\HttpFoundation\RequestStack;
+
+class RequestStackTest extends \PHPUnit_Framework_TestCase
+{
+    public function testGetCurrentRequest()
+    {
+        $requestStack = new RequestStack();
+        $this->assertNull($requestStack->getCurrentRequest());
+
+        $request = Request::create('/foo');
+
+        $requestStack->push($request);
+        $this->assertSame($request, $requestStack->getCurrentRequest());
+
+        $this->assertSame($request, $requestStack->pop());
+        $this->assertNull($requestStack->getCurrentRequest());
+
+        $this->assertNull($requestStack->pop());
+    }
+
+    public function testGetMasterRequest()
+    {
+        $requestStack = new RequestStack();
+        $this->assertNull($requestStack->getMasterRequest());
+
+        $masterRequest = Request::create('/foo');
+        $subRequest = Request::create('/bar');
+
+        $requestStack->push($masterRequest);
+        $requestStack->push($subRequest);
+
+        $this->assertSame($masterRequest, $requestStack->getMasterRequest());
+    }
+
+    public function testGetParentRequest()
+    {
+        $requestStack = new RequestStack();
+        $this->assertNull($requestStack->getParentRequest());
+
+        $masterRequest = Request::create('/foo');
+
+        $requestStack->push($masterRequest);
+        $this->assertNull($requestStack->getParentRequest());
+
+        $firstSubRequest = Request::create('/bar');
+
+        $requestStack->push($firstSubRequest);
+        $this->assertSame($masterRequest, $requestStack->getParentRequest());
+
+        $secondSubRequest = Request::create('/baz');
+
+        $requestStack->push($secondSubRequest);
+        $this->assertSame($firstSubRequest, $requestStack->getParentRequest());
+    }
+}