log.Unlock()

	got = strings.TrimSpace(got)
	want = strings.TrimSpace(want)

	if got != want {
		got, want, lines := removeCommonLines(got, want)
		t.Errorf("Log differs after %d common lines.\n\nGot:\n%s\n\nWant:\n%s\n", lines, got, want)
	}
}

func removeCommonLines(a, b string) (asuffix, bsuffix string, commonLines int) {
	for {
		nl := strings.IndexByte(a, '\n')
		if nl < 0 {