When I run this test and it fails:
func TestCaseA(t *testing.T){
t.Run("my name with spaces", func (t *testing.T){
t.Error("some error message")
})
}
then the name of the test is modified (spaces are changed to underscores) in the output:
--- FAIL: TestCaseA (0.00s)
--- FAIL: TestCaseA/my_name_with_spaces (0.00s)
main.go:10: some error message
FAIL
Why does it do this?
Here's a working example: https://play.golang.org/p/viZjC60Dazg
It's explained in this blog post: https://blog.golang.org/subtests
The full name of a subtest or sub-benchmark is a slash-separated list of its name and the names of all of its parents, starting with the top-level. The name is the corresponding function name for top-level tests and benchmarks, and the first argument to Run otherwise. To avoid display and parsing issues, a name is sanitized by replacing spaces with underscores and escaping non-printable characters. The same sanitizing is applied to the regular expressions passed to the -run or -bench flags.
Some examples could be to make it simpler for automated tools to process the test output, to avoid issues with the shell making regex arguments containing spaces appearing as multiple arguments etc. I'd rather avoid using spaces than deal with this magic renaming.
I found the most definitive answer I could, in the code itself, of course. The rewrite function comment reads
rewrite rewrites a subname to having only printable characters and no white space.
https://golang.org/src/testing/match.go#L133
As to why? I'm guessing JimB hit the nail on the head with his comment:
As for why, maybe because it's easier to reference names without spaces in the cli?
White spaces are bad for cli.