public async Task DeleteAppointmentSlotAsync_should_return_success()
{
var createResult = await sut !.CreateAppointmentSlotAsync(new LocalDateTime(2021, 5, 1, 10, 0), Period.FromHours(1), 1);
var id = (createResult as CreateAppointmentSlotResult) !.Id;
var result = await sut !.DeleteAppointmentSlotAsync(id);
Assert.IsTrue(result.Succeeded);
Assert.IsFalse(await db !.Slots.AnyAsync(s => s.Id == id));
}