godog failed to compile testmain package - but should improve the error message

[MelleKoningSGG]

Please answer these questions before submitting a bug report.

What version of godog are you using?

> godog version
Godog version is: v0.12.0

What version of Go are you using?

> go version
go version go1.15.15 linux/amd64

What did you do?

First add a /test folder and executed godog.
This provides me godog example steps -> 👍

Then added the example code in a test.go file and ran godog again

What did you expect to see?

• Execution of the steps and that godog shows the implementation is still godog.ErrPending

What did you see instead?

failed to compile testmain package: exit status 1 - output: compile: -importcfg: open /tmp/go-build685074617/b001/importcfg.link: no such file or directory

Additional context

After lots of struggle, I found out that I had to rename the test.go file to test_test.go ❗

• now I'm indeed seeing the expected results.

🔴 Strong request: Can the error message failed to compile testmain package: exit status 1 possibly become more helpful, for example telling me that I'm still missing an actual file that ends in _test.go ? A more helpful message would have gotten me back on track way sooner then the cryptic error message that is currently being displayed.

[mattwynne]

Similar to #383