Add Tests

In the comments here we can have a discussion of WHAT needs to be tested.

I have made process in writing tests, I had a heck of time getting my test runner working with my debugger. After that was done I wrote this:

/**
   * Test node edit form with new same_page_preview.
   */
  public function testNodePreviewButtons() {
    // Prerequisites.
    $assert_session = $this->assertSession();
    $page = $this->getSession()->getPage();

    // Does standard preview button?
    try {
      $assert_session->assert($page->hasButton('Preview'), "Has Preview button.");
    }
    catch (ExpectationException $e) {
      $this->fail('Original Preview button not found.');
    }

    // Does the page have our new preview buttons?
    try {
      $assert_session->assert($page->hasLink('edit-toggle-preview'), "Has Toggle Preview button.");
      $assert_session->assert($page->hasButton('edit-preview--2'), "Has Refresh Preview button.");
      $page->clickLink('edit-toggle-preview');
    }
    catch (ExpectationException | ElementNotFoundException $e ) {
      $this->fail('New Preview buttons not found.');
    }
  }

It produced these pages:

Node Add Page

Preview Pane

@brianperry @laurii
I was expected the Node Add Page to show the toggle working. Are javascript driven behaviors possible to test with FunctionalTest? Should I use FunctionalJavascript or Nightwatch instead? Is there something else you'd recommend?

I have test that work now.

Ultimately I couldn't get a Nightwatch test that installs a module to work (either the core provided test or one I created myself). I found a way to test everything with a FunctionalJavascript tests so I'll put a pin in this until I know more.