public void SendGroupMessageAsync_GroupDoesNotExists_ThrowsItemNotFoundException()
        {
            var chatId      = Guid.NewGuid().ToString();
            var messageData = new MessageDataModel()
            {
                Text = "This is a test message!"
            };

            _unitOfWork.Setup(u => u.Chats.GetByIdAsync(It.IsAny <string>())).ReturnsAsync((Chat)null);

            _messagesService.Awaiting(s => s.SendGroupMessageAsync(chatId, messageData))
            .Should().Throw <ItemNotFoundException>();
        }