Move the views data tests to a unit test

1. +++ b/core/modules/views/tests/Drupal/views/Tests/ViewsDataTest.php
   @@ -0,0 +1,477 @@
   +   * Stores a mocked module manager to invoke hooks.
   

   Maybe just 'The mocked module handler'.

2. +++ b/core/modules/views/tests/Drupal/views/Tests/ViewsDataTest.php
   @@ -0,0 +1,477 @@
   +   * $the mocked config factory.
   

   s/$the/The - unless you know something I don't about using variables in docs.. ;)

3. +++ b/core/modules/views/tests/Drupal/views/Tests/ViewsDataTest.php
   @@ -0,0 +1,477 @@
   +  public static function getInfo() {
   ...
   +  protected function setUp() {
   

   I *think* we put {@inheritdoc} here now?

4. +++ b/core/modules/views/tests/Drupal/views/Tests/ViewsDataTest.php
   @@ -0,0 +1,477 @@
   +    // \Drupal\views\ViewsDataHelper::fetchFields().
   

   @see ?

5. +++ b/core/modules/views/tests/Drupal/views/Tests/ViewsDataTest.php
   @@ -0,0 +1,477 @@
   +    $this->assertEquals(2, count($base_tables), 'The correct amount of base tables were returned.');
   

   We can use assertCount() here instead.

6. +++ b/core/modules/views/tests/Drupal/views/Tests/ViewsDataTest.php
   @@ -0,0 +1,477 @@
   +    $this->assertEquals($expected_views_data, $views_data);
   ...
   +    $this->assertEquals($expected_views_data, $views_data);
   ...
   +    $this->assertEquals(array(), $views_data);
   ...
   +    $this->assertEquals($expected_views_data, $views_data);
   ...
   +    $this->assertEquals($expected_views_data, $views_data);
   

   Do you think we should make these array comparison ones assertSame() ?

7. +++ b/core/modules/views/tests/Drupal/views/Tests/ViewsDataTest.php
   @@ -0,0 +1,477 @@
   +    $this->assertTrue(isset($views_data[$table_name]), 'Make sure the views_test_data info appears in the total views data.');
   

   assertArrayHasKey() can be used here.

I noticed that the coverage for fetchBaseTables() was incomplete, and realized that the test data was declaring the weight wrong. I decided to expand it to test all paths of the sort.

In addition, I think we've actually proven that the "If the key is invalid, return an empty array." case is unreachable code.
I cannot figure out how to arrive at that line. Either it is populated via cache, or we have $this->storage[$key] = array();.

Yay unit tests leading to removing dead code!

Actually, I meant take that one step further.

Sorry to add another chef to the kitchen here, but I really couldn't be bothered to write this down, easier to just do it. Probably same as Tim above :)

I think we should setup the mock expectations for the cache backend in some of the other test methods, as they cover cases that are not covered below by the warmCache* methods. Like calling get(), then get($table_name), then get($random_table_name).

Oh, and brought back the -50 weight, so the fetchTables gets testing with a lower and higher weight, as well as a lower/higher title. So that should exercise the sorting.

Committed and pushed to 8.x. Thanks!