Add unit tests for JSON marshal of project types

go.mod

@@ -1,5 +1,12 @@
 module github.com/nstratos/go-myanimelist
 
-go 1.16
+go 1.18
 
 require golang.org/x/oauth2 v0.0.0-20200902213428-5d25da1a8d43
+
+require (
+	github.com/golang/protobuf v1.4.2 // indirect
+	golang.org/x/net v0.0.0-20200822124328-c89045814202 // indirect
+	google.golang.org/appengine v1.6.6 // indirect
+	google.golang.org/protobuf v1.25.0 // indirect
+)

mal/mal_test.go

@@ -57,6 +57,36 @@ func testBody(t *testing.T, r *http.Request, want string) {
 	}
 }
 
+func testJSONMarshal[T any](t *testing.T, input T, want string) {
+	t.Helper()
+
+	gotOut, err := json.Marshal(input)
+	if err != nil {
+		t.Errorf("Cannot json.Marshal 'input' of type %T: %v\n\ninput value is: %#v", input, err, input)
+	}
+
+	// First we validate the wanted JSON.
+	if ok := json.Valid([]byte(want)); !ok {
+		t.Fatalf("Provided 'want' is not a valid JSON: %s", want)
+	}
+	// Then we unmarshal the wanted JSON to the same type as the input to verify
+	// that all fields decode correctly.
+	v := new(T)
+	if err := json.Unmarshal([]byte(want), v); err != nil {
+		t.Errorf("Cannot json.Unmarshal 'want' to type %T: %v\n\nwant string is: %s", input, err, want)
+	}
+	// Finally we marshal again so that the fields are sorted in order to
+	// compare the JSON strings.
+	wantOut, err := json.Marshal(v)
+	if err != nil {
+		t.Errorf("Cannot json.Marshal 'want' which has first been json.Unmarshal-ed to type %T: %v\n\nwant value is: %#v", v, err, v)
+	}
+
+	if got, want := string(gotOut), string(wantOut); got != want {
+		t.Errorf("json.Marshal(%#v) ->\n\nhave: %s\n\nwant: %s", input, got, want)
+	}
+}
+
 func testMethod(t *testing.T, r *http.Request, want string) {
 	if want != r.Method {
 		t.Errorf("Request method = %v, want %v", r.Method, want)

mal/user_test.go

@@ -6,6 +6,7 @@ import (
 	"net/http"
 	"reflect"
 	"testing"
+	"time"
 )
 
 func TestUserServiceMyInfo(t *testing.T) {
@@ -49,3 +50,64 @@ func TestUserServiceMyInfoError(t *testing.T) {
 	}
 	testErrorResponse(t, err, ErrorResponse{Err: "not_found"})
 }
+
+func TestUserMarshal(t *testing.T) {
+	testJSONMarshal(t, &User{}, "{}")
+	u := &User{
+		ID:       1,
+		Name:     "foo",
+		Picture:  "https://api-cdn.myanimelist.net/images/userimages/1.jpg?t=1653811800",
+		Gender:   "baz",
+		Birthday: "1990-01-01",
+		Location: "bar",
+		JoinedAt: time.Date(2015, 8, 20, 11, 11, 55, 0, time.UTC),
+		AnimeStatistics: AnimeStatistics{
+			NumItemsWatching:    1,
+			NumItemsCompleted:   1,
+			NumItemsOnHold:      1,
+			NumItemsDropped:     1,
+			NumItemsPlanToWatch: 1,
+			NumItems:            1,
+			NumDaysWatched:      1.1,
+			NumDaysWatching:     1.1,
+			NumDaysCompleted:    1.1,
+			NumDaysOnHold:       1.1,
+			NumDaysDropped:      1.1,
+			NumDays:             1.1,
+			NumEpisodes:         1,
+			NumTimesRewatched:   1,
+			MeanScore:           1.1,
+		},
+		TimeZone:    "America/Guyana",
+		IsSupporter: true,
+	}
+	want := `{
+		"id": 1,
+		"name": "foo",
+		"picture": "https://api-cdn.myanimelist.net/images/userimages/1.jpg?t=1653811800",
+		"gender": "baz",
+		"birthday": "1990-01-01",
+		"location": "bar",
+		"joined_at": "2015-08-20T11:11:55Z",
+		"anime_statistics": {
+			"num_items_watching": 1,
+			"num_items_completed": 1,
+			"num_items_on_hold": 1,
+			"num_items_dropped": 1,
+			"num_items_plan_to_watch": 1,
+			"num_items": 1,
+			"num_days_watched": 1.1,
+			"num_days_watching": 1.1,
+			"num_days_completed": 1.1,
+			"num_days_on_hold": 1.1,
+			"num_days_dropped": 1.1,
+			"num_days": 1.1,
+			"num_episodes": 1,
+			"num_times_rewatched": 1,
+			"mean_score": 1.1
+		},
+		"time_zone": "America/Guyana",
+		"is_supporter": true
+	}`
+	testJSONMarshal(t, u, want)
+}