util: write tests for endpoints

[Scharxi]

Write some tests to check if the endpoints do what they have to do

e.g.

package main_test

import (
	"net/http"
	"net/http/httptest"
	"testing"

	"github.com/golang/mock/gomock"
	"github.com/stretchr/testify/assert"

	"yourpackage/dataservice"
	"yourpackage/restapi"
	"yourpackage/restapi/mocks"
)

func TestGetUser(t *testing.T) {
	ctrl := gomock.NewController(t)
	defer ctrl.Finish()

	// Mock-Implementierung der Datenzugriffsschicht
	mockDataService := mocks.NewMockDataService(ctrl)
	mockDataService.EXPECT().GetUser(1).Return(&dataservice.User{ID: 1, Name: "John"}, nil)

	// REST-API-Handler initialisieren und den DataService setzen
	apiHandler := restapi.NewAPIHandler()
	apiHandler.SetDataService(mockDataService)

	// HTTP-Request und -Response simulieren
	req, _ := http.NewRequest("GET", "/users/1", nil)
	rec := httptest.NewRecorder()

	// Handler aufrufen
	apiHandler.ServeHTTP(rec, req)

	// Überprüfen der HTTP-Response
	assert.Equal(t, http.StatusOK, rec.Code)
	assert.Equal(t, `{"id":1,"name":"John"}`, rec.Body.String())
}