Comments on: Coding: API readability/testability

By: Jonathan

Jonathan — Sat, 10 Oct 2009 02:54:47 +0000

@Ryan — I just blogged about your particular solution for controlling "now". What does the "HasBeen" method do in your above example. Also, do you have any other interesting behavior/methods on your DomainTime instance?

By: Jonathan

Jonathan — Sat, 10 Oct 2009 02:39:46 +0000

We use something similar to Ryan's approach, but based upon the code he's got, I think I like his solution better. It's simply, elegant, testable, and doesn't require injection into your entity objects.

By: Phil Cleveland

Phil Cleveland — Fri, 09 Oct 2009 17:32:13 +0000

What about making the the test method (CreateForSomeSituationForTest) internal, so that the API will not be polluted? Of course you would have to setup your test fixture to have access to internal methods with this approach.

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Fri, 09 Oct 2009 15:46:10 +0000

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By: Ryan Roberts

Ryan Roberts — Fri, 09 Oct 2009 15:00:46 +0000

Yes, unfortunately. It's not a real proxy. A clock object would be more elegant, but then you get into issues around service injection into domain objects. An issue I blithely ignored by using a static dependency

By: Mark Needham

Mark Needham — Fri, 09 Oct 2009 14:48:23 +0000

@Adam – that was the other thing we were debating – forgot to mention that! Thinking was maybe a clock was a bit overkill at the moment because we only have this one test which is dependent on date. In general though I like the idea of the clock.

@Ryan – so do you use 'DomainTime' in your code instead of 'DateTime' with that approach?

By: Ryan Roberts

Ryan Roberts — Fri, 09 Oct 2009 14:42:15 +0000

I use a ..static DomainTime.Instance shim to control datetime in tests.

Ends up with something like

using(DomainTime.Is(new(DateTime(2003,10,10))
{
var model = SomeRandomModel.JustTheUsualMethod();
DomainTime.HasBeen(new TimeSpan(0,0,0,1));

Assert.AreEqual(..)
}

Where the using scope controls whether the DomainTime class returns real times or test values.

By: Adam Scott

Adam Scott — Fri, 09 Oct 2009 14:40:56 +0000

The alternative is to stub what DateTime.Today returns. However I realise that stubbing static calls is not trivial, so I guess the question becomes – how about injecting a Clock object, rather than relying on the static call?