public async Task Create_awaiting_match_if_user_has_none_awaiting_matches_already(int userId)
        {
            var awaitingMatches = new List <AwaitingMatch>
            {
                new AwaitingMatch
                {
                    UserId = 1
                },
                new AwaitingMatch
                {
                    UserId = 2
                },
                new AwaitingMatch
                {
                    UserId = 3
                },
                new AwaitingMatch
                {
                    UserId = 4
                }
            };

            var mockMatchRepo     = new Mock <IMatchRepository>();
            var mockUserRepo      = new Mock <IUserRepository>();
            var mockConfiguration = new Mock <IConfiguration>();

            mockMatchRepo.Setup(repo => repo.RetrieveAwaitingMatches())
            .ReturnsAsync(awaitingMatches.Where(x => x.UserId == userId).ToList());

            mockMatchRepo.Setup(repo => repo.AddAwaitingMatch(It.IsAny <AwaitingMatch>()))
            .Callback <AwaitingMatch>(aw =>
            {
                awaitingMatches.Add(aw);
            }).Returns(Task.CompletedTask);
            var mockMatchService = new MatchService(mockUserRepo.Object, mockMatchRepo.Object, mockConfiguration.Object);


            await mockMatchService.AddToAwaitingMatch(userId);

            var isAwaitingMatchAdded = awaitingMatches.Any(x => x.UserId == userId);


            Assert.True(isAwaitingMatchAdded);
        }