Remove the /core/modules/simpletest folder

There is a reference in a migrate test for some reason:

core/modules/file/tests/src/Kernel/Migrate/d6/FileMigrationTestTrait.php
32:      $source['site_path'] = 'core/modules/simpletest';

This should probably be updated, but not sure what to!

@longwave nice catch.

I'm pretty sure that this is due to the fact that simpletest used to have all the of the test files in it. Yep that's why.

The files all moved to 'core/test/fixtures/files' so the current setting should be 'core/test/fixtures' - and we can change this to that. FWIW this is not necessary because this is only used here:

    $site_path = $this->configuration['site_path'] ?? 'sites/default';
    $this->filePath = $this->variableGet('file_directory_path', $site_path . '/files') . '/';

And the file_directory_path is set to 'core/test/fixtures' but there is no harm in changing it in the test to something that makes sense.

We missed #4 when we did #3080163: Decouple TestFileCreationTrait::getTestFiles() from simpletest module

NW for #6.

Note that #3080163: Decouple TestFileCreationTrait::getTestFiles() from simpletest module did update the drupal6 db fixture and change the file directory path... which is why everything works. So if something in contrib was depending on the trait setting it correctly it has been long since broken... so maybe it is better to remove it. The other option would be to update the Drupal6 db in one of that test and set the D6 variable to an empty string so we can have test coverage of the fallback...

We'd need to do something like

    // Remove the file_directory_path.
    Database::getConnection('default', 'migrate')
      ->delete('variable')
      ->condition('name', 'file_directory_path')
      ->execute();

in one of the tests that use the trait.

@Spokje removing $source['site_path'] = 'core/modules/simpletest'; will work. But as per #9 this means we are lacking test coverage.

What we need to do is set it to core/test/fixtures and then in \Drupal\Tests\file\Kernel\Migrate\d6\MigrateFileTest::setUp add

    // Remove the file_directory_path to test site_path setting.
    Database::getConnection('default', 'migrate')
      ->delete('variable')
      ->condition('name', 'file_directory_path')
      ->execute();

after the call to the parent set up.

And then later in the test you will need to change the update of file_directory_path to an insert...ie...

    Database::getConnection('default', 'migrate')
      ->insert('variable')
      ->fields(['name', 'value'])
      ->values(['name' => 'file_directory_path', 'value' => serialize('files/test')])
      ->execute();

I've fixed #12. What's really interesting is that \Drupal\Tests\file\Kernel\Migrate\d6\MigrateFileTest::testFiles already has this comment:

    // Test that we can re-import and also test with file_directory_path set.
    \Drupal::database()
      ->truncate($map_table)
      ->execute();

So it seems there was an intention to test without a file_directory_path variable set - so we are now reinstating that test coverage.

Took a moment to remember that the d6 source plugin uses site_path, but got there in the end. To be sure I was reading the test correctly (still recovery from flu) I walked through the test with the debugger and found it is working as expected and no test coverage has been lost.

Off we go!

Committed/pushed to 10.1.x and cherry-picked to 10.0.x, thanks!