Mocking void methods

[Richard Banks]

If a method has a return value I can do this:

aMock.SomeMethod.Returns(args => doSomething());

but if the method is has a Void return value then the Returns() option
isn't available to me. Probably because it's an Action instead of a
Func that needs to be applied.

I'm assuming you just haven't bumped into that yet?

-- Richard

[Xerxes]

maybe i misunderstood something but if the method has a void return,
why would you want to set the Returns() on it?

[Xerxes]

more specifically - any method "returning" void, isnt actually
returning
anything, so the Returns doesnt apply anyway.

On Jul 5, 7:28 pm, Richard Banks <rbank...@gmail.com> wrote:

[David Tchepak]

Hi Richard,

We don't support Returns() on void methods because, well, because they can't return anything. :)

You raise a good point about performing an action when a void method is called though, which we do support. Adapting your example:

        [Test]

        public void VoidMethods() {

            var aSub = Substitute.For<SomeInterface>();

            aSub.When(x => x.SomeVoidMethod()).Do(x => DoSomething());

            aSub.SomeVoidMethod();

            Assert.True(_wasSomethingDone);

        }

        private void DoSomething() {

            _wasSomethingDone = true;

        }

Not quite as nice as some of the other NSub syntax, but we're hoping it's not something people will need too frequently and so won't give too much friction. 

(Btw, I'd be keen to hear any ideas for an alternative syntax, so please ping me if you come up with something. :))

Cheers,

David

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[Richard Banks]

So I can override it's behaviour.  Basically like the .Do() method in Rhino.

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[Richard Banks]

Ah.  Ok.  I didn't notice the When in the intellisense list.

Thanks :-)

P.S. For alternate syntax how about

aSub.SomeVoidMethod().Do((x,y,z) => SomethingHere(x,y,z));

[David Tchepak]

That would be our preferred syntax, but unfortunately System.Void is not a first class citizen in C#, so we can't put an extension method on it to make it work. 

(SomeVoidMethod() returns void, so can't do anything with that return. Hence resorting to lambdas.)

[Richard Banks]

Bummer. :-(

[Garth Kidd]

David, I'd appreciate a way to get an Action matching the signature of
my void method. I could then use it to call methods on the void
method's arguments.

A simplification of my current problem:

public interface IMaintainIndexes {
void RegisterIndex<T>(Predicate<T> criterion);
}

public interface IRegisterIndexes {
void RegisterIndexes(IMaintainIndexes indexer);
}

[TestFixture]
public void TestsIndexer() {
[Test]
public void CriteriaIsCalled() {
bool wasCalled = false;
var indexer = new ConcreteIndexer();
var definer = Substitute.For(IRegisterIndexes);
Func<object, bool> criterion = {
wasCalled = true;
return false;
};

// OnCallOf returns dynamic to achieve the following
definer.OnCallOf.RegisterIndexes(indexer =>
indexer.RegisterIndex<object>(criterion));

indexer.Add(new object());

// WasCalled returns dynamic, too…
definer.WasCalled.RegisterIndexes;
Assert.True(wasCalled);
}
}

The trick is that ConcreteIndexer does not implement IMaintainIndexes.
I might refactor my way around that; I did it to myself because I was
spending too much time fighting one behaviour of generics. It just
occurred to me there's a much simpler way…

Yours,
Garth.

[David Tchepak]

Hi Garth,

We're trying to avoid taking a dependency on .NET 4/dynamic at this stage, but we'll see what we can do for later releases.

With regards to your current problem, I'm not exactly sure what you're trying to achieve. If you can give me a bit more detail on what behaviour you're trying to test I'm happy to try and help out (message me off list if you like).

Regards,

David

[Louis Haußknecht]

Hi,

is this also the recommended way to throw an exception when calling a
void - method?

Cheers,

Louis

> > nsubstitute...@googlegroups.com<nsubstitute%2Bunsubscribe@googlegr oups.com>
> > .

[David Tchepak]

Hi Louis,

Yes, just replace DoSomething() in the example below with "throw new FooException()".

Regards,

David

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[Louis Haußknecht]

Okay,

so I'm throwing an exception when my void method is called.

That's working so far, but ReceivedWithAnyArgs for the same method
reports, it was not called.

Is this behavior desired?

Louis

[David Tchepak]

Hi Louis,

Are you using the latest release? This should be fixed in 0.1.3. (http://github.com/nsubstitute/NSubstitute/downloads)

If you have the latest release please let me know and we'll get it fixed. (If you can post a failing test case that would be great!)

Regards,

David

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[Louis Haußknecht]

Hi David,

it was my fault.

I had to switch to VB 9 in my current project and implemented the
delegate wrong.

Btw, in VB you have to write "sentences" like Substitute.For( of IFoo)
which looks really ulgy....

Thank's for the great work.

Louis

[David Tchepak]

"it was my fault."

Please don't ever blame yourself when you could blame VB. ;)

Do you have any suggestions for syntax that would work with VB? You can call the non-generic version which takes a type array, but I have a feeling that won't help.

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[Yann Duran]

Hi David,

 

I'll ignore your swipe at VB, lol.

 

It's unfortunate that the developers of VB chose to use "of" in generics, but we're used to it I guess, so "Substitute.For(of IFoo)" just registers on the brain as "generics", even though it doesn't read quite as nicely as "Substitute.For<SomeInterface>".

 

Maybe for VB you could have "Substitute.ForType(of IFoo)"?

 

That reads a bit better I guess. Just a thought, although I don't really think a different syntax is all that necessary to be honest. I'm not opposed to it, I just wouldn't be jumping up & down in horror at having to use the current syntax.

 

Great product btw!

 

Yann

[David Tchepak]

Thanks for the feedback Yann. I'd prefer not to add more methods to the API if VBers are happy enough with the current syntax.

Cheers,

David

[Louis Haußknecht]

I second that.

Please don't pullute the nice syntax just for VB!

Working in VB is almost always troublesome if you want to use most of
the fluent stuff with Labda's etc.

Louis

On 26 Aug., 05:09, David Tchepak <tche...@gmail.com> wrote:
> Thanks for the feedback Yann. I'd prefer not to add more methods to the API
> if VBers are happy enough with the current syntax.
>
> Cheers,
> David
>
>
>
> On Thu, Aug 26, 2010 at 12:14 PM, Yann Duran <yanndu...@gmail.com> wrote:
> >  Hi David,
>
> > I'll ignore your swipe at VB, lol.
>
> > It's unfortunate that the developers of VB chose to use "of" in generics,
> > but we're used to it I guess, so "Substitute.For(of IFoo)" just registers
> > on the brain as "generics", even though it doesn't read quite as nicely as "
> > Substitute.For<SomeInterface>".
>
> > Maybe for VB you could have "Substitute.ForType(of IFoo)"?
>
> > That reads a bit better I guess. Just a thought, although I don't really
> > think a different syntax is all that necessary to be honest. I'm not opposed
> > to it, I just wouldn't be jumping up & down in horror at having to use the
> > current syntax.
>
> > Great product btw!
>
> > Yann
>

> >  *From:* David Tchepak <tche...@gmail.com>
> > *Sent:* Thursday, August 26, 2010 10:54 AM
> > *To:* nsubs...@googlegroups.com
> > *Subject:* Re: [nsubstitute] Re: Mocking void methods

[David Tchepak]

Could always have a NSubstitute.VbSupport namespace with VB-specific methods. :)

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