Fixed failed Integration Tests

- `lib/internal/Magento/Framework/View/FileSystem.php:174` explode():
  Passing null to parameter #2 ($string) of type string is deprecated

Author: andrewbess

dev/tests/integration/testsuite/Magento/Framework/View/Element/TemplateTest.php

@@ -116,6 +116,7 @@ public function testGetObjectData()
 
     public function testGetCacheKeyInfo()
     {
+        $this->_block->setTemplate($this->_block->getTemplate() ?? '');
         $this->assertArrayHasKey('template', $this->_block->getCacheKeyInfo());
     }
 }

dev/tests/integration/testsuite/Magento/Test/Integrity/Magento/Payment/MethodsTest.php

@@ -71,6 +71,7 @@ public function testPaymentMethod($code, $methodClass)
             /** @var $block \Magento\Framework\View\Element\Template */
             $block = $blockFactory->createBlock($blockClass);
             $block->setArea('frontend');
+            $block->setTemplate($block->getTemplate() ?? '');
             $this->assertFileExists((string)$block->getTemplateFile(), $message);
             if ($model->canUseInternal()) {
                 try {
@@ -80,6 +81,7 @@ public function testPaymentMethod($code, $methodClass)
                         \Magento\Store\Model\Store::DEFAULT_STORE_ID
                     );
                     $block->setArea('adminhtml');
+                    $block->setTemplate($block->getTemplate() ?? '');
                     $this->assertFileExists((string)$block->getTemplateFile(), $message);
                     Bootstrap::getObjectManager()->get(
                         \Magento\Store\Model\StoreManagerInterface::class

dev/tests/integration/testsuite/Magento/Theme/Block/Html/FooterTest.php

@@ -30,7 +30,8 @@ public function testGetCacheKeyInfo()
         $context = $objectManager->get(\Magento\Framework\App\Http\Context::class);
         $context->setValue(Context::CONTEXT_AUTH, false, false);
         $block = $objectManager->get(\Magento\Framework\View\LayoutInterface::class)
-            ->createBlock(\Magento\Theme\Block\Html\Footer::class);
+            ->createBlock(\Magento\Theme\Block\Html\Footer::class)
+            ->setTemplate('');
         $storeId = $objectManager->get(\Magento\Store\Model\StoreManagerInterface::class)->getStore()->getId();
         $this->assertEquals(
             ['PAGE_FOOTER', $storeId, 0, $this->_theme->getId(), false, $block->getTemplateFile(), 'template' => null],