go test flag: flag provided but not defined

Question

Hi I am using a flag when testing in go:
file_test.go var ip = flag.String("ip", "noip", "test")

I am only using this in one test file. And it works fine when only testing that one test file, but when I run: go test ./... -ip 127.0.0.1 alle of the other test file saying: flag provided but not defined.

Have you seen this?

Regards

Answer 1

flag.Parse() is being called before your flag is defined.

You have to make sure that all flag definitions happen before calling flag.Parse(), usually by defining all flags inside init() functions.

Answer 2

If you've migrated to golang 13, it changed the order of the test initializer, so it could lead to something like

flag provided but not defined: -test.timeout

as a possible workaround, you can use

var _ = func() bool {
    testing.Init()
    return true
}()

that would call test initialization before the application one. More info can be found on the original thread:

https://github.com/golang/go/issues/31859#issuecomment-489889428

Answer 3

do not call flag.Parse() in any init()