G42.TimeProvider

What it it?

A way to abstract time that allows for time travel in your unit tests.

Why?

Writing DateTime.UtcNow ties your code to "right now" which causes temporal issues in unit testing. This simple package allows you to swap out how time is configured in your entire app.

For instance you can:

Use DateTime.UtcNow in production
Use SpecificTimeProvider to set the current date to an exact date\time in tests.
Use SpecificTimeProvider to advance time to a specific date\time after a step has occurred in tests.

Usage

Each provider implements ITimeProvider.

To new one up, simply new things up and call GetTime().

var provider = new SystemUtcDateTimeProvider();
var rightNow = provider.GetTime();//whatever the UTC time right now

var provider = new SpecificTimeProvider(new DateTime(1955, 11, 5);
var rightNow = provider.GetTime();//will be November 5, 1955
provider.SetTime(new DateTime(1985, 10, 26));//mutate time by travelling to Oct 26th, 1985
rightNow = provider.GetTime();//Great Scott!

Dependency Injection

var container = new UnityContainer();//obviously using Unity here
container.RegisterType<ITimeProvider, SystemUtcTimeProvider>();
OR
container.RegisterType<ITimeProvider, SpecificTimeProvider>(new SingletonLifetimeManager(), new InjectionConstructor(specificTime));

Notes

Make sure you never call DateTime.<whatever> in your code by depending on ITimeProvider.

In this way you can change then entire app's clock by simply using whatever time provider you choose.

Nuget

https://www.nuget.org/packages/G42.TimeProvider/