Using the Injectable Clock

Setup your application

In the project where you set up your services, usually the entry project of your application, add the nuget package Stravaig.Clock.DependencyInjection

In your Startup class, or where ever you build your IServiceCollection, add the following:

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services.AddClock();

Using the Clock

In any project where you use the clock include the nuget package Stravaig.Clock.

Inject the IClock in to your classes as you would any other dependency, e.g.

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public class MyService
{
  private readonly IClock _clock;
  public MyService(IClock clock)
  {
    _clock = clock;
  }
}

Then when you need to get the current time you can call the relevant method on IClock. e.g.

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public Thing CreateTheThing()
{
  var thing = new Thing()
  {
    DateCreatedUtc = _clock.UtcNow,
  };
}

Testing code that uses the IClock

In your test project you will need to add the Nuget package Stravaig.Clock.Testing.

In your test you will need to create a FakeClock to inject into your class instead of using the regular Clock the application will use when running.

e.g.

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[Test]
public void TestTheThing()
{
  // Arrange
  var createTime = new DateTime(2023, 8, 12, 14, 20, 0, DateTimeKind.Utc);
  FakeClock fakeClock = FakeClock.SetTo(createTime);
  var myService = new MyService(fakeClock);

  // Act
  var thing = myService.CreateTheThing();

  // Assert
  thing.DateCreatedUtc.ShouldBe(createTime);
}

Note: The above test uses Shouldly as the assertion framework.