Convert file.test to PSR-0

Waiting for this one before I'll continue with #1468328: Move file entity info, managed file, and file usage functionality into File module. Once this is done, it will be *much* easier to move all classes that depend on the file entity to file.module.

Doing this now.

This patch:

1. Moves helper functions from the .test file to the helper module, loading it where needed.
2. Converts the file_test helper module to PSR-0. It has dummy stream wrappers for testing. Those are now in a lib folder in the testing module. I considered putting those into the system module's lib folder instead, but it seams to be better that way, because the module declares them and other testing modules have lib folders, too.
3. Most importantly: Converts the test classes to PSR-0.
4. Remove the file[] entry from system.info.

While the test was postponed and waiting for an 8.x retest, other PSR-0 patches made it in. Yay! Chasing info file changes.

Number field tests failing looks pretty random to me. Going to test once more, before I am off to debugging this.

#5: 1598574-file-tests-psr-0-5.patch queued for re-testing.

+++ b/core/modules/system/lib/Drupal/system/Tests/File/TestBase.phpundefined
@@ -0,0 +1,213 @@
+class TestBase extends WebTestBase {

As discussed in IRC, this name is too short/generic. Same imho for HookTestBase.

I vote for FileTestBase.

Yeah.

TestBase -> FileTestBase. HookTestBase -> FileHookTestBase.

Mhh ... how could I forget 6 classes? Well spotted, @aspilicious. This one should be complete.

Yes! Great work!

$this->assertEqual($this->classname, file_stream_wrapper_get_class($this->scheme), t('Got correct class name for dummy scheme.'));

Is incorrect probably because the classname doesn't contain the namespace in it. Just hard code it for now.

This one should be fine.

Why can't we use single backslashes, I believe that is our standard.

Yeah ... no difference in single quotes strings unless at the very end, which is unlikely for class names. Only, that is the format the debug() statement I used to look up the class name serialized it.

Rdy!

Committed and pushed to 8.x! Thanks!