}
}

// Fill buf through n writes of string fus.
// The initial contents of buf corresponds to the string s;
// the result is the final contents of buf returned as a string.
func fillString(t *testing.T, testname string, buf *Buffer, s string, n int, fus string) string {
	check(t, testname+" (fill 1)", buf, s)
	for ; n > 0; n-- {
		m, err := buf.WriteString(fus)
		if m != len(fus) {