}
		if len(tt.a) > 0 {
			if want := tt.a[len(tt.a)-1] + "z"; string(x) != want {
				t.Errorf("last appended result was %s; want %s", x, want)
			}
		}
	}
}

func TestFieldsFunc(t *testing.T) {
	for _, tt := range fieldstests {
		a := FieldsFunc([]byte(tt.s), unicode.IsSpace)
		result := sliceOfString(a)
		if !slices.Equal(result, tt.a) {