The tests seem to make sense. The biggest feedback I have is that I would break the tests up.

For example, test_prepare_jitm_edit_comments test seems to actually be testing two separate things:

1. That the JITM notice displays on edit-comments if Akismet is not active
2. That the JITM notice does not display on edit-comments if Akismet is not active

While these are very similar, having separate tests might make it easier to grok and know what exactly is failing when a test fails. Same feedback for the other tests.

@ebinnion: I thought about this too, but decided to focus on the rules of a specific view v.s. breaking it up. IOW, if a unit test fails, it fails that JITM, not a specific rule of the JITM. That seemed to be the most intuitive to write. However, I see your point from the view of: "I just wrote code, why did this break?"

I agree that this makes more sense to break up into smaller tests, so I'll go ahead and do that.

I added a testsuite for JITM unit tests so now you can do

phpunit --testsuite jitm

I found one issue when running the tests:

There was 1 failure:

1) WP_Test_Jetpack_JITM::test_jitm_dismiss
Failed asserting that false is true.

/jetpack/tests/php/test_class.jetpack-jitm.php:161

IDK why, but I couldn't revert changes to yarn.lock properly.
I have fixed the failing test and added an example of how we can add explanation strings to make failures more obvious.

I've successfully reverted the yarn.lock and tested again and with Igor's fix the test now passes.
So let's 🐑