public void Execute(Guid fromAccountId, Guid toAccountId, decimal amount)
{
var from = _accountRepository.GetAccountById(fromAccountId);
var to = _accountRepository.GetAccountById(toAccountId);
//These kinds of validations could be wrapped using FluentValidation, but for simplicity because its only one validation I decided to do it in here.
//That being said, although it's only one validation we can already see code duplication in the other feature, which could go against clean code practices,
//so in the end I would actually implement a common validation setup with fluent validation to avoid that, or another strategy to avoid code validation duplications.
if (from == null || to == null)
{
throw new InvalidOperationException($" The user with account id {fromAccountId} does not exist.");
}
//If at any point any of these operations fails an exception is thrown and the changes to the entities are safely discarded.
//But usually this would be wrapped within a unit of work.
from.TryWithdrawn(amount);
to.TryTransfer(amount);
_accountRepository.Update(from);
_accountRepository.Update(to);
//Notifications are only sent after we can confirm that the transactions happened successfully.
//As explain in the account class, the preferred option, in my opinion, is to have a domain event dispatch this action using a mediator from inside the domain object.
//Whatever strategy used the key point is to avoid adding any dependencies inside the domain object unless otherwise advised by the team.
NotificationThresholds.SendIfLowFunds(_notificationService, from);
NotificationThresholds.SendIfLowFunds(_notificationService, to);
NotificationThresholds.SendIfNearPaidInLimit(_notificationService, to);
}
public void FullTest_WhenStockIsWithinThresholds_ShouldNotCreateMessage()
{
// Prepare return values
var stock = new StockInfo {
Symbol = "MSFT", Date = DateTime.Now, Value = 10.0M
};
var thresholds = new NotificationThresholds {
Symbol = "MSFT", Email = "*****@*****.**", High = 15, Low = 4
};
// Stub the StockApi
var stockApi = new Mock <IStockApi>();
stockApi
.Setup(s => s.GetStock(It.IsAny <string>()))
.Returns(Task.FromResult(stock))
.Verifiable();
// Stub the Database
var database = new Mock <IDatabase>();
database
.Setup(d => d.GetThresholds(It.IsAny <string>(), It.IsAny <string>()))
.Returns(Task.FromResult(thresholds));
// Stub the MessageService
var messageSvc = new Mock <IMessageService>();
messageSvc
.Setup(m => m.SendMessage(It.IsAny <Message>()));
// Build up feature class
var notifier = new StockThresholdNotifier(database.Object, stockApi.Object, messageSvc.Object);
// Run
notifier.CheckStock("MSFT", "*****@*****.**")
.Wait();
// Assert expected argument value
stockApi.Verify(s => s.GetStock("MSFT"));
// Assert expected argument values
database.Verify(d => d.GetThresholds("MSFT", "*****@*****.**"));
}
/// <summary>
/// This pure function creates a notification (or not) based on the stock info and thresholds.
/// </summary>
public Message MaybeCreateMessage(StockInfo stock, NotificationThresholds thresholds)
{
if (stock.Value > thresholds.High)
{
return new Message {
Email = thresholds.Email, Body = $"{stock.Symbol} exceeds the maximum value of ${thresholds.High}."
}
}
;
else if (stock.Value < thresholds.Low)
{
return new Message {
Email = thresholds.Email, Body = $"{stock.Symbol} is less than the minimum value of ${thresholds.Low}."
}
}
;
else
{
return(null);
}
}
