Add an area handler to display drupal_set_messages

D8 like.

We should add test for this as well.

Here is a quick test.

+++ b/core/modules/views/lib/Drupal/views/Tests/Handler/AreaMessageTest.php
@@ -0,0 +1,70 @@
+
+    // The handler is configured to show with empty views by default, so should
+    // appear.
+    $this->assertEqual(array('#theme' => 'status_messages'), $view->display_handler->handlers['empty']['messages']->render(), 'The expected render array was returned.');
+
+    // Turn empty off, and make sure it isn't rendered.
+    $view->display_handler->handlers['empty']['messages']->options['empty'] = FALSE;
+    // $empty parameter passed to render will still be FALSE, so should still
+    // appear.
+    $this->assertEqual(array('#theme' => 'status_messages'), $view->display_handler->handlers['empty']['messages']->render());
+    // Should now be empty as both the empty option and parameter are empty.
+    $this->assertEqual(array(), $view->display_handler->handlers['empty']['messages']->render(TRUE));
+  }

If we test such low level we could use actual unit tests right from the beginning. I don't see much of integration going on here. What do you think?

Yeah, sure. I just used an existing test and made it what I wanted :)

This could be a real unit test pretty easily. Leave it with me.

Here we go.

1. +++ b/core/modules/views/tests/Drupal/views/Tests/Plugin/area/MessagesTest.php
   @@ -0,0 +1,77 @@
   +   *
   +   * @covers ::render()
   +   */
   

   should we also add defineOptions here?

2. +++ b/core/modules/views/tests/Drupal/views/Tests/Plugin/area/MessagesTest.php
   @@ -0,0 +1,77 @@
   +    $this->assertsame(array('#theme' => 'status_messages'), $this->messagesHandler->render());
   

   you should really autocomplete more

3. +++ b/core/modules/views/tests/Drupal/views/Tests/Plugin/area/MessagesTest.php
   @@ -0,0 +1,77 @@
   +
   

   let's skip that empty line

Sorry, forgot about this issue. I guess everyone else did too. Either that or no one cares :)

10: 2210755-10.patch queued for re-testing.

Not sure I believe all of those fails.

We do care, but we just care about more than one issue

10: 2210755-10.patch queued for re-testing.

I'm confused - wouldn't this mean that the messages would be moved from one location to another if the theme has an area for displaying messages? Like what is the use-case?

Committed 04dd275 and pushed to 8.x. Thanks!