}
	return nil
}

var nl = []byte("\n")

// upcomingHeaderKeys returns an approximation of the number of keys
// that will be in this header. If it gets confused, it returns 0.
func (r *Reader) upcomingHeaderKeys() (n int) {
	// Try to determine the 'hint' size.
	r.R.Peek(1) // force a buffer load if empty
	s := r.R.Buffered()
	if s == 0 {

	}, {
		input: "A: v\r\n\r\nB: v\r\nC: v\r\n",
		want:  1,
	}, {
		input: "A: v" + strings.Repeat("\n", 1000),
		want:  1,
	}} {
		r := reader(test.input)
		got := r.upcomingHeaderKeys()
		if test.want != got {
			t.Fatalf("upcomingHeaderKeys(%q): %v; want %v", test.input, got, test.want)
		}
	}
}

func TestReadMIMEHeaderNoKey(t *testing.T) {
	r := reader(": bar\ntest-1: 1\n\n")
	m, err := r.ReadMIMEHeader()