prevCount := s.ErrorCount
	checkTok(t, s, line, s.Scan(), want, text)
	if s.ErrorCount != prevCount+1 {
		t.Fatalf("want error for %q", text)
	}
}

func countNewlines(s string) int {
	n := 0
	for _, ch := range s {
		if ch == '\n' {
			n++
		}
	}
	return n
}

func testScan(t *testing.T, mode uint) {
	s := new(Scanner).Init(makeSource(" \t%s\n"))