npm run test-unit:watch no longer supports focused tests

[talldan]

The test runner no longer seems to support changing a test to describe.only or it.only.

To reproduce:

1. Run npm run test-unit:watch
2. Change a unit test to it.only.
3. Observe that the focused test is ignored. (this might depend on which test is set to only, I noticed this while trying it on describe( 'undo' - https://github.com/WordPress/gutenberg/blob/trunk/packages/core-data/src/test/reducer.js#L144)

[gziolo]

Isn't it related to the different test runner – Jest Circus – that is used with unit tests for some time? It's a new default starting from Jest 27 that we are going to update to quite soon anyway. Maybe this issue doesn't exist in Jest 27 anymore. We can test against #33287. I doubt it's anything on the @wordpress/scripts side.

[simonhammes]

I tried to reproduce this, following the outlined steps:

1. Run npm run test-unit:watch
2. Change a unit test to it.only.
3. Observe that the focused test is ignored. (this might depend on which test is set to only, I noticed this while trying it on describe( 'undo' - https://github.com/WordPress/gutenberg/blob/trunk/packages/core-data/src/test/reducer.js#L144)

But it works for me (on trunk, using npm ci).
I modified the exact line in reducer.js to describe.only and Jest only executed this section.

[kevin940726]

I can't reproduce this either. For me, it's correctly running only the tests I specified. @talldan Could you provide more info or maybe try it with a different setup?

[talldan]

It still doesn't work for me. Here's a screenshot:

To reproduce this:

1. Run npm run test-unit:watch
2. Add a focus test in the reducer file
3. Change the name of a test in the selectors file.

Expected - only the reducer test executes because it's focused
Actual - the test runner runs the focused test in addition to the other modified tests

[kevin940726]

Oh, I think this is expected? only only focuses tests in the same file, it doesn't prevent tests in other files from running.

[talldan]

Ah, ok, fair enough, didn't realise that. Seems like a bit of a useless feature, and I don't think it previously worked that way.

[kevin940726]

I believe it always works that way though 😅 , or at least suppose to. I normally filter the files in watch mode if I only want to focus some of the tests.