FR: Test rule for running google-java-format check

[davido]

Currently we are doing this outside of the build, e.g. with this alias:

  $ alias gjf
  alias gjf='git show --diff-filter=AMR --pretty="" --name-only HEAD | grep java$ | xargs -r /home/davido/projects/gerrit/tools/format/google-java-format-1.7 -i'

On Slack @shs96c commented how this test rule could be implemented:

We’ve not got a rule for that yet, but the process of writing one is simple enough:

o Create a java_google_format_test rule (it’s important that it’s a test rule!)

o Hook it into _create_lint_tests (the pattern should be obvious)

o Optionally create a rule that when run will actually do the reformatting

o Create either a config rule or just allow people to set True as the value for the workspace’s lint_setup

Once that’s done, anyone using the java_library, java_binary, java_test or java_export rules from contrib_rules_jvm can opt into the linting framework and have the google java formatter be part of their regular test suites.

Update

Linting can be disabled by adding a no-lint tag to any rule that needs it.
And for everything in a build file by using package_lint_config(linters = {}).

It was also pointed out, that there is another PR was uploaded upstream.

[shs96c]

If we can expose the Google Format command as a *_test rule, then this will be easy to add.