codelens: don't treat TestMain as a test

[zmb3]

What version of Go, VS Code & VS Code Go extension are you using?

• Run go version to get version of Go
  • 1.14.6
• Run code -v or code-insiders -v to get version of VS Code or VS Code Insiders

1.48.0-insider
cfbd1999769f4f08dce29629fb92fdc0fac53829
x64

• Check your installed extensions to get the version of the VS Code Go extension
  • 0.16.1

Describe the bug

The feature that puts clickable "run test | debug test" on top of test functions identifies TestMain as a runnable test.

TestMain is not something that works with go test -run ..., so clicking the "run test" button results in the following slightly confusing message.

Running tool: /usr/local/bin/go test -timeout 30s -run ^TestMain$

testing: warning: no tests to run
PASS
ok  	my/pkg/here	0.153s

Would it be more clear if we simply didn't offer the run/debug button for TestMain?

Steps to reproduce the behavior:

1. Create a TestMain
2. Click on "run test"
3. See error

[hyangah]

Needs adjustment in the filters in getTestFunctions, etc.

--
FYI we are also working with gopls so gopls provides those codelenses in the future.
@mcjcloud can you please help checking if gopls is generating codelens for TestMain?

[suzmue]

I looked into this issue a bit (thanks @zmb3 for the easy repro) and just wanted to update this with some things I found and thoughts on a fix:

So it looks like 'TestMain' is actually run successfully using go test -run ... and the error is coming from the testing package from the call to m.Run(). The message is definitely confusing as the TestMain function did successfully run, m just had no tests to run.

Since it is actually possible to run this test using go test -run ... I think it would be valid to leave the 'run test, debug test' buttons on this and some people may have a use for doing so (debugging the setup or teardown code, etc).

func TestMain(t *testing.T) is considered a regular test, so a correct fix would need to check the function signature, too.

[zmb3]

Since it is actually possible to run this test using go test -run ...

I agree that it's possible to run the TestMain func using go test -run, but I'm not sure I'd call it a test. It will always say "no tests to run" and there will never be any tests that pass or fail when clicking that button, so is it the button actually useful?

If someone wants to debug the setup or teardown code, they can still put breakpoints in TestMain and click "debug test" on an actual test.

[hyangah]

since func TestMain(t *testing.T) is a regular test, yes we need to check the function signature. A heuristic would be to read the line (of the symbol's range) and see if it's including testing.M. But that's till a heuristic.

Looking at the gopls source code,
it seems that it already does do the right filtering.
We are currently in the process of delegating the code lens computation to the language server.
How about waiting for the transition to complete?

[hyangah]

I will close this issue in favor of #654.