CLI option for override steep command at spawn worker

[matsubara0507]

I think to execute Steep with Bazel and rules_ruby.
So, I writen Bazel configuration as follows.

ruby_test(
    name = "typecheck",
    main = "@bundle_example//:bin/steep",
    args = [
        "check",
        "--steepfile=example/Steepfile",
    ],
    srcs = ["Steepfile", ":lib"] + glob(["sig/**/*.rbs"]),
    deps = [":lib", "@bundle_example//:bin"],
)

But, bazel test is failed.

# Type checking files:

#<Errno::ENOENT: No such file or directory - steep>
  /.rbenv/versions/3.1.1/lib/ruby/3.1.0/open3.rb:222:in `spawn'
  /.rbenv/versions/3.1.1/lib/ruby/3.1.0/open3.rb:222:in `popen_run'
  /.rbenv/versions/3.1.1/lib/ruby/3.1.0/open3.rb:161:in `popen2'
  /execroot/rules_steep/bazel-out/darwin-fastbuild/bin/example/typecheck-test.runfiles/bundle_example/lib/ruby/3.1.0/bundler/gems/steep-64ced3af5657/lib/steep/server/worker_process.rb:36:in `spawn_worker'
  /execroot/rules_steep/bazel-out/darwin-fastbuild/bin/example/typecheck-test.runfiles/bundle_example/lib/ruby/3.1.0/bundler/gems/steep-64ced3af5657/lib/steep/server/worker_process.rb:47:in `block in spawn_typecheck_workers'
  /execroot/rules_steep/bazel-out/darwin-fastbuild/bin/example/typecheck-test.runfiles/bundle_example/lib/ruby/3.1.0/bundler/gems/steep-64ced3af5657/lib/steep/server/worker_process.rb:46:in `times'
  /execroot/rules_steep/bazel-out/darwin-fastbuild/bin/example/typecheck-test.runfiles/bundle_example/lib/ruby/3.1.0/bundler/gems/steep-64ced3af5657/lib/steep/server/worker_process.rb:46:in `each'
  /execroot/rules_steep/bazel-out/darwin-fastbuild/bin/example/typecheck-test.runfiles/bundle_example/lib/ruby/3.1.0/bundler/gems/steep-64ced3af5657/lib/steep/server/worker_process.rb:46:in `map'
  /execroot/rules_steep/bazel-out/darwin-fastbuild/bin/example/typecheck-test.runfiles/bundle_example/lib/ruby/3.1.0/bundler/gems/steep-64ced3af5657/lib/steep/server/worker_process.rb:46:in `spawn_typecheck_workers'
  /execroot/rules_steep/bazel-out/darwin-fastbuild/bin/example/typecheck-test.runfiles/bundle_example/lib/ruby/3.1.0/bundler/gems/steep-64ced3af5657/lib/steep/drivers/check.rb:38:in `run'
  /execroot/rules_steep/bazel-out/darwin-fastbuild/bin/example/typecheck-test.runfiles/bundle_example/lib/ruby/3.1.0/bundler/gems/steep-64ced3af5657/lib/steep/cli.rb:115:in `process_check'
  /execroot/rules_steep/bazel-out/darwin-fastbuild/bin/example/typecheck-test.runfiles/bundle_example/lib/ruby/3.1.0/bundler/gems/steep-64ced3af5657/lib/steep/cli.rb:52:in `run'
  /external/bundle_example/lib/ruby/3.1.0/bundler/gems/steep-64ced3af5657/exe/steep:11:in `<top (required)>'
  /execroot/rules_steep/bazel-out/darwin-fastbuild/bin/example/typecheck-test.runfiles/bundle_example/bin/steep:14:in `load'
  /execroot/rules_steep/bazel-out/darwin-fastbuild/bin/example/typecheck-test.runfiles/bundle_example/bin/steep:14:in `<main>'

Bazel is execute main wrapped by Ruby script instead of directly main executed.
And, Bazel is not set path of main to PATH environment variable in sandbox.
Therefore, Steep cannot spawn worker using Open3.popen2("steep", ...).

To solve this issue, add --steep-command option for specify command to spawn worker.
Rewrite Bazel configuration above using --steep-command option as follows then I could execute Steep with Bazel.

ruby_test(
    name = "typecheck",
    main = "@bundle_example//:bin/steep",
    args = [
        "check",
        "--steepfile=example/Steepfile",
        "--steep-command=example/typecheck", # this is Ruby script wrapped `main`
    ],
    srcs = ["Steepfile", ":lib"] + glob(["sig/**/*.rbs"]),
    deps = [":lib", "@bundle_example//:bin"],
)

I think that need --steep-command option to execute Steep with Bazel.
But, I have not idea other use-case...

[soutaro]

Thank you! 🎉