KernelTestBase ignores extensions in site-specific directories

I don't think this has anything to do with ViewsUnitTestBase and even less so with #1905334: Only load all modules when a hook gets invoked.

Apparently, *no* test modules inside tests folders in contrib modules are found on test bot, while it is working fine locally.

I've seen this in #2385503: Fix HEAD fails and also in search_api 8.x.

Try to create a web test with a dependency on your module, it will fail.

I have no idea how to fix it unfortunately, and yes, it is a D8 specific problem.

So does that mean we should move this to some testbot queue?

Right, I know about #2, but it works for us locally but it doesn't work on testbot.

Based on your description, it is the same for you.

To be able to fix it in core, we need to be able to reproduce it.

@dawehner just said that testbot still puts the module in sites/all/modules. Can you try to reproduce it if you do that as well locally?

It seems the namespace-to-directory mapping for is incorrect when the module is in sites/default/modules (sites/all/modules seems to be fine). In #2385503: Fix HEAD fails we did debug(\Drupal::service('container.namespaces')); and saw paths like /var/lib/drupaltestbot/sites/default/files/checkout///src (where the triple slash should actually be the module path).

@Berdir found a few lines in WebTestBase:

    // Save the original site directory path, so that extensions in the
    // site-specific directory can still be discovered in the test site
    // environment.
    // @see \Drupal\Core\SystemListing::scan()
    $settings['settings']['test_parent_site'] = (object) array(
      'value' => $this->originalSite,
      'required' => TRUE,
    );

Doing the same in KernelTestBase fixes it on my end.

You can't test this yourself on the testbot, we also can't write a test this in core I think, as we'd need a module in sites/default.

@Arla already verified that this works locally when you have a module with a kernel test in sites/default with this patch and not without

The only thing I can think of other than just committing it is trying to apply this patch for 8.x contrib tests to core automatically on the testbot, maybe jthorson can configure that somehow. Another way would be to configure testbot so that it puts modules in /modules on 8.x and not sites/default.

Huh.

@berdir
I guess this does not cause any kind of issues for other kernel tests so I really don't see a reason to not get it into core,
it helps contrib modules.

Let's add a comment to explain why this is needed.

If we add a comment, we should add one to WebTestBase as well, that has the same line, also without comments AFAIK (or we would have copied them)

Agreed, the added line should have an explanation. There was actually a comment in WebTestBase, see the code quote in #11. I just wasn't sure that the exact same comment applies in KernelTestBase. But I guess it does?

Updating issue title.

Oh. There's a german saying that goes like "Wer lesen kann ist klar im Vorteil" (He who can read has a clear advantage). True once more..

Yes, I think that is exactly the comment we want here.

Okay, except that the class reference in that comment was outdated with #2188661: Extension System, Part II: ExtensionDiscovery.

Looks good to me, RTBC when green.

Bug fixes to test code are not frozen in beta. Committed 5a581dd and pushed to 8.0.x. Thanks!