Always Obtaining a Future Date in C#

I was working today on building a C# REST client for a historic currency conversion web service and needed to write the unit tests.

A historic currency conversion web service it is a web service that allows the retrieval of the exchange rate of 2 currencies from a specified past date. In order to prevent the user from sending a bad data to the service, I employed some simple measures to verify the user input.

In order to simulate error cases in the unit tests I needed to find a method to create a date that will always be in the future. Below you can see my solution:

	//The RIGHT way
	[Test]
	public void GetConversionRate_DateFutureParameter_ThrowsException()
	{
	//This will always return a date that will be in the future
	DateTime future = DateTime.Now.AddYears(1);
	Assert.Throws( typeof(CurrencyConversionException),
	() => GrandTrunkCurrencyConversionService.Instance
	.GetConversionRate(TEST_CURRENCY_NAME_US_DOLLAR,
	TEST_CURRENCY_NAME_AU_DOLLAR,
	future) );
	}
	//The NOT SO RIGHT way
	[Test]
	public void GetConversionRate_DateFutureParameter_ThrowsException()
	{
	//Perhaps no one will run this unit test in 10 years. But what if
	//someone will?
	DateTime notReallyFuture = new DateTime(2023,1,1);
	Assert.Throws( typeof(CurrencyConversionException),
	() => GrandTrunkCurrencyConversionService.Instance
	.GetConversionRate(TEST_CURRENCY_NAME_US_DOLLAR,
	TEST_CURRENCY_NAME_AU_DOLLAR,
	notReallyFuture) );
	}

view raw CSharp_Nunit_AlwaysObtainAFutureDate_Example.cs hosted with ❤ by GitHub

The main idea is that you will never know for how much time your software will be used, so it's better to play it safe :-).

Q: Since I was talking about past and future, what is the oldest library you wrote and still use today?

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