Breakpoints do not work in packages with a TestMain(*testing.M) function

[jnathanh]

1. What version of Delve are you using (dlv version)?
   • 1.22.1
2. What version of Go are you using? (go version)?
   • go version go1.22.0 darwin/arm64
3. What operating system and processor architecture are you using?
   • macOS 14.5, arm64
4. What did you do?

   $ dlv test ./withtestmain -- -test.run ^TestDebug$
   #Type 'help' for list of commands.
   (dlv) b TestDebug:1
   #Breakpoint 1 set at 0x1021c23cc for github.com/jnathanh/delve-test-main/withtestmain_test.TestDebug() #./withtestmain/debug_test.go:13
   (dlv) c

5. What did you expect to see?

   > github.com/jnathanh/delve-test-main/withouttestmain.TestDebug() ./withouttestmain/debug_test.go:9 (hits goroutine(21):1 total:1) (PC: 0x1001c5e6c)
    4:         "fmt"
    5:         "testing"
    6: )
    7:
    8: func TestDebug(t *testing.T) {
   =>   9:         fmt.Println("stopping on a breakpoint in this test works with delve")
   10: }

6. What did you see instead?

   TestMain
   Process 52848 has exited with status 0

To repro:

Clone this repo and try and stop on a breakpoint in the TestDebug function in the withtestmain package. Setting the breakpoint succeeds, but I am unable to stop on it. You can do the same in the withouttestmain package without a problem. The only material difference is the presence of a TestMain function, with the *testing.M parameter.

I originally encountered this in vscode executing the "debug test" functionality and it took a few hours to narrow down the issue. Ideally the breakpoint would work, but if that is not possible, I would at least want delve to throw an error or output a warning to indicate the issue and give some indication of how I can work around it.

[aarzilli]

If you write your own TestMain function you are supposed to call m.Run() yourself, otherwise no tests will be run: https://beta.pkg.go.dev/testing#hdr-Main.