Add ReturnsSelf extension method?

[Meyrick Kirby]

If I have a simple interface as such:

public interface ISimple{
    ISimple Do();
}

I can mock the Do method to return the mock using the Returns extension method:

ISimple simple = Substitute.For<ISimple>();
simple.Do().Returns(simple);
ISimple act = simple.Do();
Equal(simple, act);

But it would be nice if I could simply call a ReturnsSelf extension method:

ISimple simple = Substitute.For<ISimple>();
simple.Do().ReturnsSelf();
ISimple act = simple.Do();
Equal(simple, act);

[David Tchepak]

Hi!

Thank you for this suggestion! There is a problem implementing this because here the `ReturnsSelf()` extension method will not have a reference to self (`simple`). It will only get a reference to whatever `Do()` returns (in this case it will default to a new substitute).

We do have a different feature designed to help with these sort of builder patterns which you might be interested in instead. There is an extension called `ReturnsForAll<T>(T value)`, which will make all methods on a substitute that return `T` return the specific `value`. You will first need to bring this into scope with `using NSubstitute.Extensions;`. Here is an example:

using NSubstitute;

using NSubstitute.Extensions;

using NUnit.Framework;

namespace NSubTestWorkshop {

    public interface ISimple {

        ISimple Do();

    }

    [TestFixture]

    public class SampleTests {

        [Test]

        public void Sample() {

            var simple = Substitute.For<ISimple>();

            simple.ReturnsForAll<ISimple>(simple); // don't actually need the explicit generic here. I just added it for clarity

            var act = simple.Do();

            Assert.AreSame(simple, act);

        }

    }

}

Now any calls to `simple` that return an `ISimple` (if the interface had multiple builder-style methods) will return the self reference. You can override specific ones that need to behave differently using standard `.Returns()`.

Hope this helps.

Regards,

David

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[Meyrick Kirby]

David,

Thanks for the prompt reply.

I think that helps.

Meyrick