Test running gazelle rule in another workspace

[jayconrod]

Test should:

• Create a new workspace with a WORKSPACE file, BUILD.bazel file, and some trivial source files, using the recommended boilerplate code.
• bazel run //:gazelle
• bazel build a newly generated go_binary rule.

This test should work similarly to rules_go integration tests (see bazel_tests.bzl).

[achew22]

I have done something like this in the iBazel project. I opted to just use sh_library in my examples but the same logic applies.

https://github.com/bazelbuild/bazel-watcher/blob/a2ceacd14ddf2cb7e1afe718f181441cc95162b3/e2e/simple/simple_test.go#L19-L31

It also has the added bonus of allowing you to verify against multiple versions of Bazel in unison by passing in a set of versions.

[jayconrod]

@achew22 Thanks, that looks promising.