FakeItEasy deep nested types faking

Question

I have a complex object that I'm trying to fake.

interface IContext
{
    User User { get; }
}

A.CallTo(
    () => _fakeContext.User.Subscription.Attributes)
    .Returns(new List<Attribute>());

But I get the next exception:

The current proxy generator can not intercept the specified method for the following reasons: - Non virtual methods can not be intercepted

All nested types are properties, and they are simple anemic types with get; set; property modifiers. And when I look into the debugger they all are fakes.

Is there any way to setup the last property of the chain and avoid setuping all previous ones?

Are the property on `User` virtual? If so could you post the source code for `User`? — Xharze, Jan 17 '13 at 15:42
No. Neither User nor Subscription are virtual. It's code from the compiled assembly. — Akim Khalilov, Jan 17 '13 at 16:24
FakeItEasy cannot mock non virtual methods, so you have to resolve to build the object youself. Something like the answer below would do the trick. — Xharze, Jan 17 '13 at 18:34

k.m · Accepted Answer · 2013-01-17T16:28:29.410

If your objects are anemic enough, you might want to give AutoFixture a go:

var fake = A.Fake<>();
var fixture = new Fixture();
// If it's possible [1], AutoFixture will generate entire object graph
var user = fixture.CreateAnonymous<User>();
// Since data will be random [2], you can overwrite properties as you like
user.User.Subscription.Attributes = new List<Attributes>();
A.CallTo(() => fake.User).Returns(user);

In order for it to work, your custom objects need to have public constructor and preferably avoid using interfaces (but that can be mitigated with auto-mocking extensions, like AutoFakeItEasy).
The .Build method provides fluent API to customize objects autogeneration, so the randomness can be controlled

FakeItEasy deep nested types faking

1 Answers1