public async Task DeleteByIdAsync_Deletes_ContactAsync() { using (var dbContext = ContactDbContextInMemory.CreateInMemoryDbContext()) { //Arrange var contact1 = new Contact { Id = 9, FirstName = "test1" }; var contact2 = new Contact { Id = 10, FirstName = "test2" }; var contact3 = new Contact { Id = 11, FirstName = "test3" }; dbContext.Contacts.Add(contact1); dbContext.Contacts.Add(contact2); dbContext.Contacts.Add(contact3); dbContext.SaveChanges(); //Act var sut = new ContactRepository(dbContext); await sut.DeleteByIdAsync(9, It.IsAny <CancellationToken>()); var result = sut.GetByIdAsync(9, It.IsAny <CancellationToken>()); //Assert Assert.Null(result.Result); } }