Convert File Managed API tests to DrupalUnitTestBase

1: file-managed-dubt-2194085-1.patch queued for re-testing.

That was a fun one to figure out. DrupalUnitTestBase::(un)registerStreamWrapper() was completely messed up, no idea how no other tests are failing.

Yeah, now I'm officially scared...

8: file-managed-dubt-2194085-8.patch queued for re-testing.

Green :)

1. +++ b/core/modules/simpletest/lib/Drupal/simpletest/DrupalUnitTestBase.php
   @@ -427,15 +427,12 @@ protected function registerStreamWrapper($scheme, $class, $type = STREAM_WRAPPER
        // @see https://drupal.org/node/2028109
   -    // Add the stream wrapper to the file_get_stream_wrappers() static cache,
   -    // only set the ALL type so that other types will be recalculated when
   -    // requested.
        $wrappers = &drupal_static('file_get_stream_wrappers', array());
   -    $wrappers[STREAM_WRAPPERS_ALL][$scheme] = array(
   +    $wrappers[$scheme] = array(
          'type' => $type,
          'class' => $class,
        );
   -    $wrappers[$type][$scheme] = $wrappers[STREAM_WRAPPERS_ALL][$scheme];
   +    $wrappers[STREAM_WRAPPERS_ALL] = $wrappers;
      }
   

   Nope, the validator test fails and the reason is that this code is completely weird, first it's adding it to the top level and then adds all of it recursively to the ALL wrapper.

   Maybe that function worked like this at one point, but it doesn't in HEAD. And fixing that then requires the other fixes, which are somehow magically hidden by this weird stuff ;)

2. +++ b/core/modules/simpletest/lib/Drupal/simpletest/DrupalUnitTestBase.php
   @@ -452,18 +449,9 @@ protected function unregisterStreamWrapper($scheme) {
   -        }
   -      }
   -    }
   +    unset($wrappers[$scheme]);
   +    unset($wrappers[STREAM_WRAPPERS_ALL][$scheme]);
      }
    
   

   The unset relies the same weirdness and doesn't require any checks because unset($wrapper[whatever]) works fine as long as $wrapper is defined, even if the variable is NULL.

Changes look good to me.

I'm still a bit confused by the drupal_static() behavior though.

I would assume that after a call to drupal_static_reset(), drupal_static('bla', array()) would return the passed default value and not NULL, which apparently still exists as an explicit value in there? I can see that file_get_stream_wrappers() calls it with no default value, so that would initialize it to NULL, but it also immediately .... oh I see. If file_get_stream_wrappers() is called and is empty, then it loads all stream wrappers but if system.module isn't around, then it doesn't find any and $wrappers_storage is never initialized as no value is ever set.

I think if we make sure that the default value is an empty array(), possibly even pre-initialize STREAM_WRAPPERS_ALL => array(), then we could IMHO better deal with that situation because the current would behavior would result in a constant re-initialization every time it is called and it is always an array?

The result is that the comment in the patch is wrong, the problem is not that file_get_stream_wrappers() is *not* called, the problem is that it *is* called but no stream wrapper hook was found.

What do you think about this?

This doesn't need that comment/check at all and it prevents us from invoking the hook possibly multiple times, even if it's just something that could happen in a DUBT test.