testFlags []string // Additional flags accepted by this test
}

// bgCommand returns a go test Cmd and a post-Run flush function. The result
// will write its output to stdout and stderr. If stdout==stderr, bgCommand
// ensures Writes are serialized. The caller should call flush() after Cmd exits.
func (opts *goTest) bgCommand(t *tester, stdout, stderr io.Writer) (cmd *exec.Cmd, flush func()) {