Fix debug:form dateTime

Author: yceruto

src/Symfony/Component/Form/Command/DebugCommand.php

@@ -115,7 +115,7 @@ protected function execute(InputInterface $input, OutputInterface $output)
                 sort($options[$k]);
             }
         } else {
-            if (!class_exists($class)) {
+            if (!class_exists($class) || !is_subclass_of($class, FormTypeInterface::class)) {
                 $class = $this->getFqcnTypeClass($input, $io, $class);
             }
             $resolvedType = $this->formRegistry->getType($class);

src/Symfony/Component/Form/Tests/Command/DebugCommandTest.php

@@ -66,6 +66,15 @@ public function testDebugSingleFormType()
         $this->assertContains('Symfony\Component\Form\Extension\Core\Type\FormType (Block prefix: "form")', $tester->getDisplay());
     }
 
+    public function testDebugDateTimeType()
+    {
+        $tester = $this->createCommandTester();
+        $tester->execute(['class' => 'DateTime'], ['decorated' => false, 'interactive' => false]);
+
+        $this->assertEquals(0, $tester->getStatusCode(), 'Returns 0 in case of success');
+        $this->assertContains('Symfony\Component\Form\Extension\Core\Type\DateTimeType (Block prefix: "datetime")', $tester->getDisplay());
+    }
+
     public function testDebugFormTypeOption()
     {
         $tester = $this->createCommandTester();