How to test this func in handler.go?

description.md

I can run those tests on my local machine where I have mongo instance spinned up. But what about CI/CD services like Travis-CI?

How do I approach this?

handler.go

func Registration(w http.ResponseWriter, r *http.Request) {
	var res model.ResponseResult
	var user model.User

	w.Header().Set("Content-Type", "application/json")

	jsonDecoder := json.NewDecoder(r.Body)
	jsonDecoder.DisallowUnknownFields()
	defer r.Body.Close()

	// check if there is proper json body or error
	if err := jsonDecoder.Decode(&user); err != nil {
		res.Error = err.Error()
		// return 400 status codes
		w.WriteHeader(http.StatusBadRequest)
		json.NewEncoder(w).Encode(res)
		return
	}

	// Connect to mongodb
	client, _ := mongo.NewClient(options.Client().ApplyURI("mongodb://127.0.0.1:27017"))
	ctx, _ := context.WithTimeout(context.Background(), 10*time.Second)
	err := client.Connect(ctx)
	if err != nil {
		panic(err)
	}
	defer client.Disconnect(ctx)
	// Check if username already exists in users datastore, if so, 400
	// else insert user right away
	collection := client.Database("test").Collection("users")
	filter := bson.D{{"username", user.Username}}
	var foundUser model.User
	err = collection.FindOne(context.TODO(), filter).Decode(&foundUser)
	if foundUser.Username == user.Username {
		res.Error = UserExists
		// return 400 status codes
		w.WriteHeader(http.StatusBadRequest)
		json.NewEncoder(w).Encode(res)
		return
	}

	pass, err := bcrypt.GenerateFromPassword([]byte(user.Password), bcrypt.DefaultCost)
	if err != nil {
		res.Error = err.Error()
		// return 400 status codes
		w.WriteHeader(http.StatusBadRequest)
		json.NewEncoder(w).Encode(res)
		return
	}
	user.Password = string(pass)

	insertResult, err := collection.InsertOne(context.TODO(), user)
	if err != nil {
		res.Error = err.Error()
		// return 400 status codes
		w.WriteHeader(http.StatusBadRequest)
		json.NewEncoder(w).Encode(res)
		return
	}

	// return 200
	w.WriteHeader(http.StatusOK)
	res.Result = fmt.Sprintf("%s: %s", UserCreated, insertResult.InsertedID)
	json.NewEncoder(w).Encode(res)
	return
}

handler_test.go

func TestRegistration(t *testing.T) {
	t.Run("test if user already exists", func(t *testing.T) {
		jsonStr := []byte(`{"username":"santosh", "password": "password"}`)

		requestOne, _ := http.NewRequest("POST", "/register", bytes.NewBuffer(jsonStr))
		requestTwo, _ := http.NewRequest("POST", "/register", bytes.NewBuffer(jsonStr))
		responseOne := httptest.NewRecorder()
		responseTwo := httptest.NewRecorder()

		Registration(responseOne, requestOne)
		Registration(responseTwo, requestTwo)

		assertStatus(t, responseTwo.Code, http.StatusBadRequest)
	})

	t.Run("test if returns 200 on success", func(t *testing.T) {
		jsonStr := []byte(`{"username":"john", "password": "password"}`)

		request, _ := http.NewRequest("POST", "/register", bytes.NewBuffer(jsonStr))
		response := httptest.NewRecorder()

		Registration(response, request)

		got := response.Code
		want := http.StatusOK

		assertStatus(t, got, want)
	})