public async Task CheckIfCountryExistsReturnsFalseIfCountryDoesntExists() { var options = new DbContextOptionsBuilder <ApplicationDbContext>() .UseInMemoryDatabase(databaseName: Guid.NewGuid().ToString()).Options; var dbContext = new ApplicationDbContext(options); var addressesServiceMock = new Mock <IAddressesService>(); var citiesRepository = new EfDeletableEntityRepository <City>(dbContext); var repository = new EfDeletableEntityRepository <Country>(dbContext); var citiesServiceMock = new Mock <CitiesService>(citiesRepository, addressesServiceMock.Object); var service = new CountriesService(repository, citiesServiceMock.Object); var country = new Country() { Id = 1, }; dbContext.Add(country); await dbContext.SaveChangesAsync(); var result = await service.CheckIfCountryExists(2); Assert.False(result); }