compare

The package compare facilitates the comparison of two Go values providing a detailed error message in case when the comparison fails.

It is intended to be used during testing with its main objective being the comparison of large and deeply nested values.

Example

type Author struct {
	FirstName string
	LastName  string
}

type Publisher struct {
	Name string
	HQ   interface{}
}

type Book struct {
	ISBN       interface{}
	Title      string
	ReleasedAt time.Time
	Authors    []*Author
	Publisher  *Publisher
}

func TestExample(t *testing.T) {
	got := &Book{
		ISBN:       4101001545,
		Title:      "海辺のカフカ",
		ReleasedAt: time.Date(2005, time.March, 1, 0, 0, 0, 0, time.UTC),
		Authors: []*Author{{
			LastName:  "村上",
			FirstName: "春樹",
		}},
		Publisher: &Publisher{
			Name: "新潮社",
			HQ:   "JP",
		},
	}
	want := &Book{
		ISBN:       "0099458322",
		Title:      "Kafka on the Shore",
		ReleasedAt: time.Date(2005, time.October, 6, 0, 0, 0, 0, time.UTC),
		Authors: []*Author{{
			FirstName: "Haruki",
			LastName:  "Murakami",
		}},
		Publisher: &Publisher{
			Name: "Vintage",
			HQ:   nil,
		},
	}

	if err := Compare(got, want); err != nil {
		t.Error(err)
	}
}

The output of which would look something like this: