public async Task CreateCustomerShouldUpdateExistingCustomer() { var options = new DbContextOptionsBuilder <WHMSDbContext>().UseInMemoryDatabase(databaseName: Guid.NewGuid().ToString()).Options; using var context = new WHMSDbContext(options); context.Customers.Add(new Customer { Email = "*****@*****.**", FirstName = "Pesho", LastName = "Peshov", PhoneNumber = "000000" }); await context.SaveChangesAsync(); var service = new CustomersService(context); var model = new CustomerViewModel { Email = "*****@*****.**", FirstName = "Test", LastName = "Testov", PhoneNumber = "123451234" }; await service.CreateOrUpdateCustomerAsync(model); var dbCustomer = context.Customers.FirstOrDefault(); Assert.NotNull(dbCustomer); Assert.Equal("*****@*****.**", dbCustomer.Email); Assert.Equal("Test", dbCustomer.FirstName); Assert.Equal("Testov", dbCustomer.LastName); Assert.Equal("123451234", dbCustomer.PhoneNumber); }