MQE-1118: Handle XML merge failures gracefully

- Added Test and made error a tiny bit more specific (error is caught by child classes given context)

Author: aljcalandra

dev/tests/unit/Magento/FunctionalTestFramework/Test/Config/ActionGroupDomTest.php

@@ -6,6 +6,7 @@
 namespace Tests\unit\Magento\FunctionalTestFramework\Test\Config;
 
 use Magento\FunctionalTestingFramework\Exceptions\Collector\ExceptionCollector;
+use Magento\FunctionalTestingFramework\Config\Dom\ValidationException;
 use Magento\FunctionalTestingFramework\Test\Config\ActionGroupDom;
 use Magento\FunctionalTestingFramework\Util\MagentoTestCase;
 
@@ -29,4 +30,20 @@ public function testActionGroupDomStepKeyValidation()
         $this->expectException(\Exception::class);
         $exceptionCollector->throwException();
     }
+
+    /**
+     * Test Action Group invalid XML
+     */
+    public function testActionGroupDomInvalidXmlValidation()
+    {
+        $sampleXml = "<actionGroups>
+            <actionGroup name=\"actionGroupWithoutArguments\">
+                <wait>
+            </actionGroup>
+         </actionGroups>";
+
+        $exceptionCollector = new ExceptionCollector();
+        $this->expectException(ValidationException::class);
+        new ActionGroupDom($sampleXml, 'bad.xml', $exceptionCollector);
+    }
 }

src/Magento/FunctionalTestingFramework/Config/Dom.php

@@ -366,7 +366,7 @@ protected function initDom($xml, $filename = null)
         try {
             $dom->loadXML($xml);
         } catch (\Exception $exception) {
-            throw new ValidationException($filename . "\n");
+            throw new ValidationException("XML Parse Error: $filename\n");
         }
         if ($this->schemaFile) {
             $errors = self::validateDomDocument($dom, $this->schemaFile, $this->errorFormat);