Allow kernel test classes to define their own routes

Which routes are you thinking would benefit from this?

I know there are a lot of test routes inside test modules, but those are often useful in other circumstances -- e.g. I've been reusing some of them for the drupalGet() in core conversions.

This is a great idea - would be good to have an example of an existing test we can convert - not in this issue because we're still working through kernel http request things but for an example of the sort of boilerplate we should be able to remove.

> but one possible way to be able use the same route across multiple kernel tests would be to put the #[Route] method in a trait.

True.

Though one drawback of this occurs to me -- if the route is defined in a kernel test, then you can't ever test that route manually. That's sometimes useful when developing or debugging tests.

Should the existing test you mentioned in #8 be converted?

10-4

I ran the test-only locally since I can't run the job anymore (thank you gitlab)

Behat\Mink\Exception\ExpectationException: Current response status code is 500, but 200 expected.
/var/www/html/vendor/behat/mink/src/WebAssert.php:888
/var/www/html/vendor/behat/mink/src/WebAssert.php:145
/var/www/html/core/tests/Drupal/KernelTests/KernelTestHttpRequestTest.php:111


Test code or tested code printed unexpected output: Uncaught PHP Exception Error: "Call to private method Drupal\Core\Routing\AttributeRouteDiscovery::createRouteCollection() from scope Drupal\KernelTests\KernelTestAttributeRouteDiscovery" at /var/www/html/core/tests/Drupal/KernelTests/KernelTestAttributeRouteDiscovery.php line 22

MR is small and don't see any open threads. No objections.

The Needs Review Queue Bot tested this issue. It no longer applies to Drupal core. Therefore, this issue status is now "Needs work".

This does not mean that the patch necessarily needs to be re-rolled or the MR rebased. Read the Issue Summary, the issue tags and the latest discussion here to determine what needs to be done.

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Nice work on the rebase -- the private -> protected fix on AttributeRouteDiscovery and the string-based $kernelTestClass constructor look right, and that null check in collectRoutes() is a good safety net.

One nitpick on the "remove unnecessary loop" commit: that loop wasn't just noise it hit the route twice with two different testMarkup values, which is really the whole point here (proving the route reflects live state from the test class, not just that it resolves). Collapsing to one string loses that. Genuinely curious why it got cut though, might be missing context. Mind adding back a second check with a different value? Doesn't need the loop, just two assertions.
Rest of the chnages looks solid, no other concerns.

I don't have anything to add with regard to a code review. It looks OK to me.

To test this issue I attempted a route conversion of my own by embedding a test route in its test. The first route that I found that's used by a Kernel test is binary_file_response_test.download, whose test is BinaryFileResponseTestController. I copied the controller function to the test class, added the Route attribute, and then deleted the entire test module. The test module only contained the one route. The test continued to pass after performing the conversion. So that's exciting. We can eliminate that test module after this issue lands.

This one looks good to me.

This looks great. Would not have imagined it would be approx ~8 lines of actual code.

Like @joachim I sometimes manually install test modules and visit routes to debug things, but I don't think I've needed to do that for a kernel test route, only for ones in functional js/functional tests. Also with a kernel test it's easier to debug the entire code flow because it's in a single process. I think the DX of being able to see the route logic in the same place that it's tested outweighs this anyway, as well the convenience when writing tests.

Committed/pushed to main and 11.x, thanks!