Missing test dependencies

Experimenting to see what's wrong ... it looks like parent::setUp() is failing for the MimeMailRulesTestCase.

Tests aren't starting because testbots are currently down - see https://twitter.com/drupal_infra/status/1019616733957644288

Sigh.

OK, it's been so long since I've seen this problem that I almost forgot all about it. I guess the Mime Mail tests haven't run green on the drupal.org testbot for years ...

Anyway, I believe the problem is that the testbot only knows about dependent modules declared in the .info file, and when it builds the test environment it only loads the modules that are declared in the .info. So when the Mime Mail test tries to enable rules, entity, and entity_token in the setUp(), the testbot doesn't have these modules available and setUp() fails. (The tests work locally for me because I have those modules on my Drupal site.)

The solution is to name these modules as test_dependencies[] in the .info file. The testbot will build the test environment to include any modules that are named in test_dependencies[].

The problem is, these test_dependencies[] needs to be committed to the repository BEFORE the tests will work - the test_dependencies[] will have no effect if they are added as part of a patch.

So here's a patch that just adds the test_dependencies[]. The tests won't run green until AFTER this patch is committed.

An explanation of this can be found at #2181107: test fails when adding another contrib module to enable in setUp() ...

I think we can also trigger the testbot to load the test dependencies this way:

composer.json needs regular dependencies as well as test dependencies. Trying again...

OK, to summarize:

The D7 tests are currently failing because the testbot environment doesn't include Rules or Entity. This is because the testsbot parses the mimemail.info file to figure out what modules are needed in the testbot environment. Mime Mail does NOT depend on Rules or Entity, but it can use them if they are available. And in particular, Mime Mail tests DO use these modules. But since they're not required, they're not declared as dependencies in mimemail.info so the testbot doesn't load them and the tests that need these modules fail.

So the solution is to tell the testbot that these modules need to be downloaded into the testbot environment.

There are two ways to do this:

1. The patch in #7 adds these modules as test_dependencies[] so that the testbot knows they are needed for tests (and only for tests - they won't be enabled when Mime Mail is installed normally). This patch needs to be committed FIRST, and then any test runs after that should be green.
2. OR, the patch in #10 adds a composer.json to the Mime Mail project. The testbot will use this composer.json file to resolve dependencies, thus it will know it needs Rules, and Entity

I prefer method 1), as it is entirely Drupal without the need for composer.

Regardless, one of these patches should be committed so we can use the testbot again for Mime Mail.

And the D7 tests are now running and passing!