Cover change with Unit Tests

Author: lbajsarowicz

app/code/Magento/Theme/Test/Unit/Plugin/CollectionTest.php

@@ -0,0 +1,53 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+declare(strict_types=1);
+
+namespace Magento\Theme\Test\Unit\Plugin;
+
+use Magento\Framework\Data\Collection;
+use Magento\Theme\Plugin\Data\Collection as CollectionPlugin;
+use PHPUnit\Framework\MockObject\MockObject;
+use PHPUnit\Framework\TestCase;
+
+class CollectionTest extends TestCase
+{
+    /** @var MockObject|Collection */
+    private $dataCollectionMock;
+
+    protected function setUp(): void
+    {
+        $this->dataCollectionMock = $this->getMockBuilder(Collection::class)
+            ->disableOriginalConstructor()
+            ->onlyMethods(['getLastPageNumber'])
+            ->getMock();
+    }
+
+    public function testCurrentPageIsNotOverriddenIfFirstPage()
+    {
+        // Given
+        $currentPagePlugin = new CollectionPlugin();
+
+        // Expects
+        $this->dataCollectionMock->expects($this->never())
+            ->method('getLastPageNumber');
+
+        // When
+        $currentPagePlugin->afterGetCurPage($this->dataCollectionMock, 1);
+    }
+
+    public function testCurrentPageIsOverriddenIfNotAFirstPage()
+    {
+        // Given
+        $currentPagePlugin = new CollectionPlugin();
+
+        // Expects
+        $this->dataCollectionMock->expects($this->once())
+            ->method('getLastPageNumber');
+
+        // When
+        $currentPagePlugin->afterGetCurPage($this->dataCollectionMock, 2);
+    }
+}