It.IsAny<decimal> throws "System.decimal is not a supported constant type"

[dinismvcorreia]

I was using Moq 4.5.3. and decided to update Moq Nuget package to the latest version, which is 4.5.8.
Suddenly, a lot of my tests started to fail. I found that the issue occurs when using It.IsAny<decimal> on decimal optional arguments. It throws "System.decimal is not a supported constant type". It also happens in version 4.5.7.
Simple, silly test:

public interface IFoo { bool Method(decimal decimalArg = 0m); }

public class Some
{
    public int SomeMethod(IFoo foo) => foo.Method(10m) ? 1 : 0;
}

[TestFixture]
public class SomeTests
{
    [Test]
    public void SampleTest()
    {
        var fooMock = new Mock<IFoo>();
        fooMock.Setup(m => m.Method(It.IsAny<decimal>())).Returns(true);

        var sut = new Some();
        var actual = sut.SomeMethod(fooMock.Object);

        Assert.That(actual, Is.EqualTo(1));
    }
}

[kzu]

Closed? Why?

[dinismvcorreia]

Sorry, kzu, my bad. Pressed the wrong button. Anyway, I've edited the initial issue. Now, with the code sample I've supplied, it's easier to reproduce the issue.

[richardlawley]

The bug actually occurs when the object is constructed, therefore a much simpler repro is:

public interface IFoo { bool Method(decimal decimalArg = 0m); }

[TestClass]
public class SomeTests
{
    [TestMethod]
    public void SampleTest()
    {
        var fooMock = new Mock<IFoo>();
        var sut = fooMock.Object;
    }
}

[richardlawley]

As mentioned in this SO post, this is related to a Castle Core bug: castleproject/Core#87

[kzu]

So what are we missing? A dependency bump only? PR? ;)

[MichaelLogutov]

Any news on that? We're facing false negatives all around :)

[dampee]

Has anyone found a solution for this?

[i4004]

@dampee You can use alpha version of Moq (4.6.25-alpha).

[dampee]

@i4004 thanks. I have reverted to 4.2 yesterday. Can't upgrade to prerelease versions currently. Looking forward to the release.

[brianbegy]

Any update on this issue?

[tidusjar]

I've just run into this issue. 😢

[pipelf]

same problem here.

[jaredpar]

I hit what I believe is a similar issue trying to mock some Visual Studio Interfaces:

System.Runtime.InteropServices.DispatchWrapper is not a supported constant type.

It does appear to be a dupe of the castle bug: castleproject/Core#87

In my tests I was able to work around this by upgrading the Castle NuGet package to 4.0.0-beta002.

[kzu]

We've now bumped to Castle 4.0 stable, so it should be fixed