enhance(local executor): print to stdout via client field

[cognifloyd]

While working on adding tests for exec() in #336, I found that I needed a way to see what the local executor is printing to stdout.

By printing to a stdout field on the local executor, we can allow those tests to capture stdout and make sure the executor is behaving correctly.

[codecov]

Codecov Report

Merging #339 (e2f1c47) into master (6c8171c) will increase coverage by 0.01%.
The diff coverage is 80.43%.

@@            Coverage Diff             @@
##           master     #339      +/-   ##
==========================================
+ Coverage   81.17%   81.18%   +0.01%     
==========================================
  Files          68       68              
  Lines        5274     5293      +19     
==========================================
+ Hits         4281     4297      +16     
- Misses        849      851       +2     
- Partials      144      145       +1     

Impacted Files	Coverage Δ
executor/local/api.go	13.95% <0.00%> (ø)
executor/local/build.go	77.66% <76.19%> (ø)
executor/local/opts.go	96.51% <76.92%> (-3.49%)	⬇️
executor/local/local.go	100.00% <100.00%> (ø)
executor/local/service.go	93.87% <100.00%> (ø)
executor/local/stage.go	86.30% <100.00%> (ø)
executor/local/step.go	90.32% <100.00%> (ø)
executor/setup.go	100.00% <100.00%> (ø)

[jbrockopp]

Do you think this function should be exported (public)?

I could be missing something but it appears like it would only be used for testing purposes.

If so, I wonder if it should be unexported (private) like withStreamRequests()?

worker/executor/local/opts.go

Lines 147 to 156 in 0a0f0bd

	// withStreamRequests sets the streamRequests channel in the executor client for Linux
	// (primarily used for tests).
	func withStreamRequests(s chan message.StreamRequest) Opt {
	return func(c *client) error {
	// set the streamRequests channel in the client
	c.streamRequests = s
	return nil
	}
	}

[cognifloyd]

withStreamRequests is used by tests in the same package (executor.local). But, WithMockStdout is used in a different package (executor) for tests in yet another package (I want to write tests for the exec() function in package main under cmd/vela-worker)

worker/executor/setup.go

Lines 97 to 114 in 0a0f0bd

	func (s *Setup) Local() (Engine, error) {
	logrus.Trace("creating local executor client from setup")
	// create new Local executor engine
	//
	// https://pkg.go.dev/github.com/go-vela/worker/executor/local?tab=doc#New
	return local.New(
	local.WithBuild(s.Build),
	local.WithHostname(s.Hostname),
	local.WithPipeline(s.Pipeline),
	local.WithRepo(s.Repo),
	local.WithRuntime(s.Runtime),
	local.WithUser(s.User),
	local.WithVelaClient(s.Client),
	local.WithVersion(s.Version),
	local.WithMockStdout(s.Mock),
	)
	}

So, I'm open to not exporting it, but I didn't see a good way to allow tests in other packages to trigger it.

[jbrockopp]

LGTM