t.Errorf("Is4(%q) = %v; want %v", tt.ip, got4, tt.is4)
		}

		got6 := tt.ip.Is6()
		if got6 != tt.is6 {
			t.Errorf("Is6(%q) = %v; want %v", tt.ip, got6, tt.is6)
		}
	}
}

func TestIs4In6(t *testing.T) {
	tests := []struct {
		ip        Addr
		want      bool
		wantUnmap Addr
	}{
		{Addr{}, false, Addr{}},
		{mustIP("::ffff:c000:0280"), true, mustIP("192.0.2.128")},