MAGETWO-66666: Adding a product to cart from category page with an expired session does not allow product to be added

- Add unit test in case Expired session

Author: YuliyaLabudova

app/code/Magento/Checkout/Test/Unit/Controller/Cart/AddTest.php

@@ -0,0 +1,79 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+namespace Magento\Checkout\Test\Unit\Controller\Cart;
+
+use Magento\Framework\TestFramework\Unit\Helper\ObjectManager as ObjectManagerHelper;
+
+class AddTest extends \PHPUnit\Framework\TestCase
+{
+    /**
+     * @var ObjectManagerHelper
+     */
+    private $objectManagerHelper;
+
+    /**
+     * @var \Magento\Framework\Data\Form\FormKey\Validator|\PHPUnit_Framework_MockObject_MockObject
+     */
+    private $formKeyValidator;
+
+    /**
+     * @var \Magento\Framework\Controller\Result\RedirectFactory|\PHPUnit_Framework_MockObject_MockObject
+     */
+    private $resultRedirectFactory;
+
+    /**
+     * @var \Magento\Framework\App\RequestInterface|\PHPUnit_Framework_MockObject_MockObject
+     */
+    private $request;
+
+    /**
+     * @var \Magento\Framework\Message\ManagerInterface|\PHPUnit_Framework_MockObject_MockObject
+     */
+    private $messageManager;
+
+    public function setUp()
+    {
+        $this->formKeyValidator = $this->getMockBuilder(\Magento\Framework\Data\Form\FormKey\Validator::class)
+            ->disableOriginalConstructor()->getMock();
+        $this->resultRedirectFactory =
+            $this->getMockBuilder(\Magento\Framework\Controller\Result\RedirectFactory::class)
+            ->disableOriginalConstructor()->getMock();
+        $this->request = $this->getMockBuilder(\Magento\Framework\App\RequestInterface::class)
+            ->disableOriginalConstructor()->getmock();
+        $this->messageManager = $this->getMockBuilder(\Magento\Framework\Message\ManagerInterface::class)
+            ->disableOriginalConstructor()->getMock();
+
+        $this->objectManagerHelper = new ObjectManagerHelper($this);
+        $this->add = $this->objectManagerHelper->getObject(
+            \Magento\Checkout\Controller\Cart\Add::class,
+            [
+                '_formKeyValidator' => $this->formKeyValidator,
+                'resultRedirectFactory' => $this->resultRedirectFactory,
+                '_request' => $this->request,
+                'messageManager' => $this->messageManager
+            ]
+        );
+    }
+
+    /**
+     * Test for method execute.
+     *
+     * @return void
+     */
+    public function testExecute()
+    {
+        $redirect = $this->getMockBuilder(\Magento\Framework\Controller\Result\Redirect::class)
+            ->disableOriginalConstructor()
+            ->getMock();
+        $path = '*/*/';
+
+        $this->formKeyValidator->expects($this->once())->method('validate')->with($this->request)->willReturn(false);
+        $this->messageManager->expects($this->once())->method('addErrorMessage');
+        $this->resultRedirectFactory->expects($this->once())->method('create')->willReturn($redirect);
+        $redirect->expects($this->once())->method('setPath')->with($path)->willReturnSelf();
+        $this->assertEquals($redirect, $this->add->execute());
+    }
+}