add coverage test

Author: thomas-kl1

app/code/Magento/Cms/Test/Unit/Model/Config/Source/BlockTest.php

@@ -0,0 +1,64 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+namespace Magento\Cms\Test\Unit\Model\Config\Source;
+
+/**
+ * Class BlockTest
+ */
+class BlockTest extends \PHPUnit\Framework\TestCase
+{
+    /**
+     * @var \Magento\Cms\Model\ResourceModel\Block\CollectionFactory|\PHPUnit_Framework_MockObject_MockObject
+     */
+    protected $collectionFactory;
+
+    /**
+     * @var \Magento\Cms\Model\Config\Source\Block
+     */
+    protected $block;
+
+    /**
+     * Set up
+     *
+     * @return void
+     */
+    protected function setUp()
+    {
+        $objectManager = new \Magento\Framework\TestFramework\Unit\Helper\ObjectManager($this);
+
+        $this->collectionFactory = $this->createPartialMock(
+            \Magento\Cms\Model\ResourceModel\Block\CollectionFactory::class,
+            ['create']
+        );
+
+        $this->block = $objectManager->getObject(
+            \Magento\Cms\Model\Config\Source\Block::class,
+            [
+                'collectionFactory' => $this->collectionFactory,
+            ]
+        );
+    }
+
+    /**
+     * Run test toOptionArray method
+     *
+     * @return void
+     */
+    public function testToOptionArray()
+    {
+        $blockCollectionMock = $this->createMock(\Magento\Cms\Model\ResourceModel\Block\Collection::class);
+
+        $this->collectionFactory->expects($this->once())
+            ->method('create')
+            ->will($this->returnValue($blockCollectionMock));
+
+        $blockCollectionMock->expects($this->once())
+            ->method('toOptionIdArray')
+            ->will($this->returnValue('return-value'));
+
+        $this->assertEquals('return-value', $this->block->toOptionArray());
+    }
+}