if n := strings.Count(output, "Header"); n != 2 {
		t.Errorf("expected 2 headers, got %d", n)
	}
	if n := strings.Count(output, "\n"); n != 2 {
		t.Errorf("expected 2 lines, got %d", n)
	}
}

func TestDiscard(t *testing.T) {
	l := New(io.Discard, "", 0)
	s := strings.Repeat("a", 102400)
	c := testing.AllocsPerRun(100, func() { l.Printf("%s", s) })
	// One allocation for slice passed to Printf,