ACP2E-1445: Customer data in Local Storage not reset when session file lost

 - Added the test coverage.

Author: devarul

app/code/Magento/Customer/Test/Unit/Model/App/FrontController/DeleteCookieWhenCustomerNotExistPluginTest.php

@@ -0,0 +1,56 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+declare(strict_types=1);
+
+namespace Magento\Customer\Test\Unit\Model\App\FrontController;
+
+use Magento\Customer\Model\App\FrontController\DeleteCookieWhenCustomerNotExistPlugin;
+use Magento\Framework\App\Response\Http as ResponseHttp;
+use Magento\Customer\Model\Session;
+use PHPUnit\Framework\MockObject\MockObject;
+use PHPUnit\Framework\TestCase;
+
+/**
+ * Tests \Magento\Customer\Model\App\FrontController\DeleteCookieWhenCustomerNotExistPluginTest.
+ */
+class DeleteCookieWhenCustomerNotExistPluginTest extends TestCase
+{
+    /**
+     * @var DeleteCookieWhenCustomerNotExistPlugin
+     */
+    protected DeleteCookieWhenCustomerNotExistPlugin $plugin;
+
+    /**
+     * @var ResponseHttp|MockObject
+     */
+    protected ResponseHttp|MockObject $responseHttpMock;
+
+    /**
+     * @var Session|MockObject
+     */
+    protected MockObject|Session $customerSessionMock;
+
+    /**
+     * Set up
+     */
+    protected function setUp(): void
+    {
+        $this->customerSessionMock = $this->createMock(Session::class);
+        $this->responseHttpMock = $this->createMock(ResponseHttp::class);
+        $this->plugin = new DeleteCookieWhenCustomerNotExistPlugin(
+            $this->responseHttpMock,
+            $this->customerSessionMock
+        );
+    }
+
+    public function testBeforeDispatch()
+    {
+        $this->customerSessionMock->expects($this->once())
+            ->method('getCustomerId')
+            ->willReturn(0);
+        $this->plugin->beforeDispatch();
+    }
+}