[FR]: Support adding testonly to a glob of folders/files with gazelle plugin

[Aghassi]

What is the current behavior?

You can't isolate out a folder and say "for this folder, please give me source targets and add testonly to make sure this folder doesn't get used in production". This means we can do build file generation on a folder like mocks but we have to manually add testonly.

Describe the feature

We should be able to pass a directive like #gazelle:treat_as_testonly **/mocks/** that will generate targets in any mocks folder found, but add testonly to the ts_project target. This prevents anything from mocks being used downstream and ending up in production.

[jbedard]

Could this not be handled using js_test_files?

[Aghassi]

Could this not be handled using js_test_files?

In this case it would treat the mocks as test files I believe and generate a test target for them. I think this may be acceptable. But I would have to do it for every mocks folder right?

[jbedard]

You can just configure it once so mocks have their own "test target". In your root BUILD you can just do:

# gazelle:js_test_files mocks **/mocks/**

Then anywhere that glob finds files you'll get the extra target:

ts_project(name = "mocks", testonly = True, srcs = [...])

[shanshanzhu]

Is there any documentation on what glob pattern we should use?

This glob cannot find the mocks folder in our code base and there is no logging to help debug

# gazelle:js_test_files mocks **/mocks/**

[alexeagle]

@shanshanzhu do you have a minimal repro of that problem? I think @jbedard is claiming that no work is needed here.

[shanshanzhu]

#847

I tried to add a preliminary test cases to show the idea. But I'm not sure how to run the test.

Basically

1. We expect a BUILD.bazel in every folder to contain ts_project with correct testOnly attribute.
2. We expect adding this in the root BUILD.bazel will create the BUILD.bazel for every folder for us.

# gazelle:js_test_files mocks **/__mocks__/**
# gazelle:js_test_files **/*.test.ts