JabbR.Services.ChatService.RemoveAdmin C# (CSharp) Method

        public void RemoveAdmin(ChatUser admin, ChatUser targetUser)
        {
            // Ensure the user is admin
            EnsureAdmin(admin);

            if (!targetUser.IsAdmin)
            {
                // If the target user is NOT an admin, then throw
                throw new InvalidOperationException(String.Format("'{0}' is not an admin.", targetUser.Name));
            }

            // Make the user an admin
            targetUser.IsAdmin = false;
            _repository.CommitChanges();
        }

            public void ThrowsIfActingUserIsNotAdmin()
            {
                var repository = new InMemoryRepository();
                var nonAdmin = new ChatUser
                {
                    Name = "foo",
                    IsAdmin = false
                };
                var user = new ChatUser
                {
                    Name = "foo2",
                    IsAdmin = true
                };
                repository.Add(nonAdmin);
                repository.Add(user);

                var service = new ChatService(new Mock<ICache>().Object, repository);

                Assert.Throws<HubException>(() => service.RemoveAdmin(nonAdmin, user));
            }