NullReferenceException in Pose.Helpers.StubHelper.GetMatchingShimIndex about pose HOT 15 OPEN

I've noticed that Assert statements tend to break Pose. I'm currently looking into it, but in the meantime you can do this instead:

using System;
using Microsoft.VisualStudio.TestTools.UnitTesting;
namespace Pose.Tests.Fails
{
    [TestClass]
    public class ShimFails
    {
        public class MyClass
        {
            public int MyProperty { get; set; }
        }

        [TestMethod]
        [ExpectedException(typeof(NullReferenceException))]
        public void ShimConstructor()
        {
            Shim ctorShim = Shim.Replace(() => new MyClass())
                .With(() => new MyClass { MyProperty = 10 });
            
            int prop = 0;

            PoseContext.Isolate(() =>
            {
                prop = new MyClass().MyProperty;
            }, ctorShim);

            // this line breaks the Shim
            Assert.AreEqual(10, prop);
        }
    }
}

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@tjrobinson if the client test actually calls the code in the controller instead of making an actual http request you should be fine. I'm looking into this as well as the other issues you raised. Have you been able to get some other tests to work with Pose?

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Also what's happening here is that a stub is passing a null method to be rewritten.

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if the client test actually calls the code in the controller instead of making an actual http request you should be fine

Yep, I think it would be. Unfortunately these are deliberate integration tests to check the API layer. I have other tests for the MediatR commands/queries that the controllers use.

I haven't got any other tests working with Pose yet as I've not tried yet.

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Alrighty. Do try if/when you can and let me know if you run into anymore problems. Thanks

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@tjrobinson I'm curious, what made you think the error was from Pose.Helpers.StubHelper.GetMatchingShimIndex? The exception stack trace doesn't include it. Also I notice you're using Pose directly in source code form, you can update your local with this branch https://github.com/tonerdo/pose/tree/stub-enhancements and try the code again. Paste the exception output here, I added a few things to make it easier to track the origin of exceptions like this

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@tonerdo GetMatchingShimIndex was coming up in the stack trace when I was trying a few things out earlier on though as you noticed, it's not in the one above. I think it's a different trace because I tried to simplify the failing scenario and ended up with a variation on the problem. Sorry I don't have the earlier stack trace anymore.

I can't try the stub-enhancements branch at the moment but will if I get time at some other point .

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@tonerdo I have the same Null Reference Exception popping up. And tracked it down to GetRuntimeMethodForVirtual

The following code throws the null reference exception.

using System;
using Microsoft.VisualStudio.TestTools.UnitTesting;
namespace Pose.Tests.Fails
{
    [TestClass]
    public class ShimFails
    {
        public class MyClass
        {
            public int MyProperty { get; set; }
        }

        [TestMethod]
        [ExpectedException(typeof(NullReferenceException))]
        public void ShimConstructor()
        {
            Shim ctorShim = Shim.Replace(() => new MyClass())
                .With(() => new MyClass { MyProperty = 10 });

            PoseContext.Isolate(() =>
            {
                // this line breaks the Shim
                Assert.AreEqual(10, 10);

            }, ctorShim);
        }

    }
}

It was trying to find: RuntimeType.GetTypeInfo but the actual method name was System.Reflection.TypeInfo.System.Reflection.IReflectableType.GetTypeInfo(). I tried to return that but it didn't seem to help.

After that I was getting confused.

Hope this helps.

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I tried looking into the issue. Unfortunately I haven't found a solution yet. I tried the following:

1. The RuntimeMethodForVirtual returns null after which GetIndexOfMatchingShim will fail.
   In the Assert case Type is System.RunTimeType and methodInfo is GetTypeInfo

        public static MethodInfo GetRuntimeMethodForVirtual(Type type, MethodInfo methodInfo)
        {
            BindingFlags bindingFlags = BindingFlags.Instance | (methodInfo.IsPublic ? BindingFlags.Public : BindingFlags.NonPublic);
            Type[] types = methodInfo.GetParameters().Select(p => p.ParameterType).ToArray();
            return type.GetMethod(methodInfo.Name, bindingFlags, null, types, null);
        }

2. One solution I tried was to find the method in anotherway. ie:

        public static MethodInfo GetRuntimeMethodForVirtual(Type type, MethodInfo methodInfo)
        {
            BindingFlags bindingFlags = BindingFlags.Instance | (methodInfo.IsPublic ? BindingFlags.Public : BindingFlags.NonPublic);
            Type[] types = methodInfo.GetParameters().Select(p => p.ParameterType).ToArray();
            MethodInfo foundMethod = type.GetMethod(methodInfo.Name, bindingFlags, null, types, null);
            if (foundMethod == null)
            {
                MethodInfo[] methods = type.GetMethods(BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic);
                foundMethod = methods.FirstOrDefault(i => i.Name.EndsWith(methodInfo.Name));
                return foundMethod;
            }
            return foundMethod;
        }

The name of the method it find is: "System.Reflection.IReflectableType.GetTypeInfo" (this is not the FullName, but the normal Name.

But running this results in crashing the debugger.

3. Next I tried to simply run the original method whenever RuntimeMethodForVirtual returned NULL but I that resulted in a invalid program.

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@jonkeda Problem with Assert.AreEqual caused by explicit implementation of IReflectableType.GetTypeInfo() in

class System.Reflection.IntrospectionExtensions
{
  public static TypeInfo GetTypeInfo(this Type type)
  {
    if (type == (Type) null)
      throw new ArgumentNullException(nameof (type));
    return ((IReflectableType) type).GetTypeInfo();
   }
}

this is the reason why
public static MethodInfo GetRuntimeMethodForVirtual(Type type, MethodInfo methodInfo)
returns null

there is a case to reproduce this issue

interface IMyTest
{
   int ExplicitMethod();
}

class MyTest : IMyTest
{
   int IMyTest.ExplicitMethod() => 1;
}

[TestMethod]
public void TestExplicit()
{
    Shim shim = Shim.Replace(() => Is.A<IMyTest>().ExplicitMethod()).With((IMyTest t) => 42);
    var r =  new MyTest();
    PoseContext.Isolate(() => { var foo = ((IMyTest)r).ExplicitMethod(); }, shim);
 }

I haven't solve this problem yet but if your know an elegant and easy way to get explicitly implemented members, i would like to hear about it

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@Daxaker It isn't anywere near elegant, but I do have a working 'solution'.

1. if the method isn't found then look if a method exists which name ends with the method to find. (brrr)

        public static MethodInfo GetRuntimeMethodForVirtual(Type type, MethodInfo methodInfo)
        {
            BindingFlags bindingFlags = BindingFlags.Instance | (methodInfo.IsPublic ? BindingFlags.Public : BindingFlags.NonPublic);
            Type[] types = methodInfo.GetParameters().Select(p => p.ParameterType).ToArray();
            var method = type.GetMethod(methodInfo.Name, bindingFlags, null, types, null);
            if (method == null)
            {
                MethodInfo[] methods = type.GetMethods(BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic);
                MethodInfo foundMethod = methods.FirstOrDefault(i => i.Name.EndsWith(methodInfo.Name));
                return foundMethod;
            }
            return method;
        }

2. Expand the SignatureEquals to also look for interfaces.

    private static bool SignatureEquals(Shim shim, Type type, MethodBase method)
        {
            if (shim.Type == null || type == shim.Type)
                return $"{shim.Type}::{shim.Original.ToString()}" == $"{type}::{method.ToString()}";

            if (type.IsSubclassOf(shim.Type))
            {
                if ((shim.Original.IsAbstract || !shim.Original.IsVirtual)
                        || (shim.Original.IsVirtual && !method.IsOverride()))
                {
                    return $"{shim.Original.ToString()}" == $"{method.ToString()}";
                }
            }

            if (shim.Type.IsAssignableFrom(type))
            {
                if ((shim.Original.IsAbstract || !shim.Original.IsVirtual)
                    || (shim.Original.IsVirtual && !method.IsOverride()))
                {
                    return $"{shim.Original.ToString()}" == $"{method.ToString()}"
                        || method.Name.EndsWith(shim.Original.Name) ;
                }
            }

            return false;
        }

This code works for your testcase. But isn't very elegant or fail safe.

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@Daxaker many thanks for this repro. Will take a look and work on a fix

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@tonerdo Glad to be helpful

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My issue indeed had to do with calling xUnit Assert() method within the Isolate() function. Moving my assert methods out fixed the error for me.

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Has this problem fixed in a new distribution?
Or is it a normative way to act in isolate context and to assert outside?

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