public async Task AddAccessKey_ValidData_Ok()
        {
            var result = await UserService.AddAccessKey(10);

            Assert.NotNull(result);
            Assert.Equal(DateTime.UtcNow.Date.AddYears(1), result.Expiration.Date);
            Assert.True(Guid.TryParse(result.Key, out _));
            Assert.Equal(10, result.OwnerId);
            Assert.Equal(AccessKeyState.Active, result.State);
        }
        public async Task AddAccessKey_InactiveUser_Throws()
        {
            var user = DbContext.UserSet.Find(10);

            user.IsActive = false;
            DbContext.SaveChanges();

            var result = await Assert.ThrowsAsync <AccessKeyException>(() => UserService.AddAccessKey(10));

            Assert.Equal("User id 10 is not active", result.Message);
        }
        public async Task AddAccessKey_NonExistingUser_Throws()
        {
            var result = await Assert.ThrowsAsync <AccessKeyException>(() => UserService.AddAccessKey(50));

            Assert.Equal("User id 50 does not exist", result.Message);
        }