if !eq(result, tt.a) {
			t.Errorf("Fields(%q) = %v; want %v", tt.s, a, tt.a)
			continue
		}

		if string(b) != tt.s {
			t.Errorf("slice changed to %s; want %s", string(b), tt.s)
		}
		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) {