Last Updated: 06 Nov 2013 10:30 by Ovidiu

Since I upgraded my JustMock I was unable to debug ASP.NET projects. I accidentally found a resolution to the problem here:

"If you are using Telerik JustMock as a mocking framework and have recently updated it to the 2013 Q3 version, it causes this exact problem. I was able to resolve this issue by uninstalling the mocking framework and installing the 2013 Q2 version."

So I uninstalled JustMock and everything came to normal.

Last Updated: 16 Jan 2019 08:51 by ADMIN
Created by: Michael
Comments: 4
Type: Bug Report
Creating a share link with Visual Studio Live Share does not work if you have the JustMock profiler enabled. We specifically have to disable the JustMock profiler in order for VS Live Share to create sharing links. This has been reproduced by several different members of our team.

Could this please be looked into? Thanks!
Last Updated: 05 Dec 2019 15:24 by ADMIN
The debugger arrowhead pointer is not positioned to the correct execution line when debugging .Net Core. Stepping the code line by line advances the yellow arrowhead pointer based on the initial offset/messed position. When the arrowhead leaves the method the remaining lines are executed at once.
Last Updated: 18 Jun 2019 08:43 by ADMIN
There is a different behaviour when mocking the same method using the following two Arrange overrides:

public static FuncExpectation<TResult> Arrange<TResult>(Expression<Func<TResult>> expression);
public static FuncExpectation<TResult> Arrange<T, TResult>(T obj, Func<T, TResult> func);

Repro project attached. Steps to reproduce:
1. Open attached solution
2. In Tests.cs, run JustMockArrangeQueryableTest - it passes
3. Run JustMockArrangeQueryableTest2 - it fails with a invalid cast exception on the Residents collection.
Last Updated: 23 Jul 2018 12:48 by Stefan
My team and I have spotted some odd behaviour with the latest version of JustMock (2015.3.929.5) when targeting a Windows Store app.

If we create a mock for an object in a helper method, the mock fails when making assertions for calls to the mock.

The following code illustrates the issue:

        public void ThisWillFail()
            var subject = CreateSubject();


            subject.Assert(s => s.DoSomething(), Occurs.Once());

        public void ThisWillPass()
            var subject = Mock.Create<ISubject>();


            subject.Assert(s => s.DoSomething(), Occurs.Once());

        public interface ISubject
            void DoSomething();

        private static ISubject CreateSubject()
            return Mock.Create<ISubject>();

In this code, the first test will fail but the second test will pass. The only difference is that, in the first test, we're setting up the mock in a helper method.

We have a "Unit Test Library (.NET for Windows Store apps)" referencing the Telerik.JustMock assembly. I have attached a simple project containing this implementation.

It's worth noting that the same code passes in a regular .NET class library; it only fails in a "Unit Test Library (.NET for Windows Store apps)". It's also worth noting that this worked under an older version of the assembly (2014.3.1021.2).

Any help would be appreciated, as we currently have around 3,000 tests and a good proportion of them set up their mocks using a helper method in this way.

William Cowell
Last Updated: 29 Nov 2017 12:53 by ADMIN
Tests fail when run with vstest.console.exe but pass when run from VS2015.

Findings: The problematic scenario includes reference to Microsoft.WindowsAzure.ServiceRuntime.dll and usage of the RoleEnvironment class. When the RoleEnvironment class is used in a test project without JustMock and runned from vstest.console the exception will be thrown as well. Here is the exact exception: 
System.TypeInitializationException: The type initializer for 'Microsoft.WindowsAzure.ServiceRuntime.RoleEnvironment' threw an exception. ---> System.TypeInitializationException: The type initializer for '<Module>' threw an exception. ---> <CrtImplementationDetails>.ModuleLoadException: The C++ module failed to load while attempting to initialize the default appdomain.
 ---> System.Runtime.InteropServices.COMException: Invalid operation. (Exception from HRESULT: 0x80131022)
Stack Trace:
    at System.Runtime.InteropServices.Marshal.ThrowExceptionForHRInternal(Int32 errorCode, IntPtr errorInfo)
   at <CrtImplementationDetails>.GetDefaultDomain()
   at <CrtImplementationDetails>.DoCallBackInDefaultDomain(IntPtr function, Void* cookie)
   at <CrtImplementationDetails>.LanguageSupport.InitializeDefaultAppDomain(LanguageSupport* )
   at <CrtImplementationDetails>.LanguageSupport._Initialize(LanguageSupport* )
   at <CrtImplementationDetails>.LanguageSupport.Initialize(LanguageSupport* )
--- End of inner exception stack trace ---
    at <CrtImplementationDetails>.LanguageSupport.Initialize(LanguageSupport* )
   at .cctor()
--- End of inner exception stack trace ---
    at Microsoft.WindowsAzure.ServiceRuntime.RoleEnvironment.InitializeEnvironment()
   at Microsoft.WindowsAzure.ServiceRuntime.RoleEnvironment..cctor()
--- End of inner exception stack trace ---
    at Microsoft.WindowsAzure.ServiceRuntime.RoleEnvironment.get_IsAvailable()

Workaround: the vstest.console.exe could be started with parameter /InIsolation, which runs the tests in an isolated process. Here is the link to the command line options:
Last Updated: 20 May 2019 09:26 by ADMIN
A class property get wrongly mocked when used as parameter for arranging other class methods. The following sample demonstrates the scenario:

class Foo
	public string Prop{ get; set; }

	public void Bar(string val)

public void Sample()
	var sut = Mock.Create<Foo>(Behavior.CallOriginal);

	Mock.Arrange(() => sut.Bar(sut.Prop)).DoNothing();
Last Updated: 18 Jun 2019 08:37 by ADMIN
The integration between JustMock and dotCover stopped working with R2 2019. The result when code coverage is started is that all tests remain in pending state and does not finish while the CPU is idle.
Last Updated: 20 May 2019 09:32 by ADMIN
Mocking an async calls alse triggers hidden mocking of the return type. Depending of the type it might cause unexpected behavior or exception.
Last Updated: 15 Jan 2020 09:58 by ADMIN
The JustMock tests are failing when the "Test platform version" option in the JustMock VSTest v.2 task is set to value "Installed by Tools Installer".
Last Updated: 05 Dec 2019 15:32 by ADMIN

Visual Studio debugger arrowhead pointer is messed when profiler is enabled with .Net Core 2.1, in VS2107/2019


  • Use elevated features like static mocking using JustMock
  • Enable profiler from VS JustMock extension
  • Run the test in debug mode

Code Snippet

Mock.SetupStatic(typeof(ElasticOperationsHelper), Behavior.Strict, StaticConstructor.Mocked);

Mock.Arrange(() => elasticRepository.IndexDocumentInElastic<IndexDocText>(Arg.IsAny<IndexDocText>(), Arg.IsAny<string>(), null)).Returns(response);


While debugging it's found the arrowhead pointer of VS debugger is messed up and pointing to wrong line numbers. It's quite difficult to develop unit tests at this situation. Is there any resolution of this problem.

I found an article in the support page has been declined due to same problem. Is this totally dependent on "CLR" fix and .Net profiler. If so could you please provide me the Bug details of Microsoft for the same?

I would also like to know why it's necessary to have profiler enabled for scenarios like "Static Mocking", "Non virtual method mocking", "Private Mocking" etc. 

Is this only happening for .Net core? 

Hyland Software is evaluating this product as their Mocking framework for unit testing of all .net core projects.

If there is no solution, how can any prospective customer consider this as a good fit for their usage? If there is any workaround possible at this moment?

Last Updated: 24 Sep 2019 10:06 by ADMIN
The execution of JustMock tests stoped working in Visual Studio. The exact version is 16.2.1. The error message is: "The profiler must be enabled to mock, arrange or execute the specified target."
Last Updated: 04 Nov 2013 16:02 by ADMIN
using NUnit.Framework;
using Telerik.JustMock;

namespace Example
    public class MyClass
        public MyClass(int a = 5) { }

    public class TestMyClass
        public void test_MyClass()

Telerik.JustMock.MockException : Can not instantiate proxy of class: Example.MyClass.
Could not find a parameterless constructor.
   at Telerik.JustMock.Core.MocksRepository.Create(Type type, MockCreationSettings settings)
   at Telerik.JustMock.MockBuilder.Create(MocksRepository repository, Type type, Object[] constructorArgs, Nullable`1 behavior, Type[] additionalMockedInterfaces, Nullable`1 mockConstructorCall, IEnumerable`1 additionalProxyTypeAttributes, List`1 supplementaryBehaviors, List`1 fallbackBehaviors, List`1 mixins)
   at Telerik.JustMock.Mock.<>c__DisplayClass5b`1.<Create>b__5a()
   at Telerik.JustMock.Core.ProfilerInterceptor.GuardInternal[T](Func`1 guardedAction)
   at Telerik.JustMock.Mock.Create[T](Behavior behavior, Object[] args)
   at Example.TestMyClass.test_MyClass() in c:\users\micah\Documents\Source\Test\Test\Class1.cs:line 17#0

This appears to be related to the recent fix for "Improve exception message for Mock.Create".  Without Behavior.CallOriginal it works.  Supplying a parameter also works.
Last Updated: 17 May 2013 12:29 by Mohd
Created by: Mihail
Comments: 1
Type: Bug Report
Since JustMock Q1 2013 Mock.DoNotUseProfiler() is marked as an obsolete method and I cannot compile my test project. Revert it back.
Last Updated: 17 May 2013 12:23 by David
I'm getting this argument exception:
System.ArgumentException : The type or method has 3 generic parameter(s), but 2 generic argument(s) were provided. A generic argument must be provided for each generic parameter.
   at System.RuntimeType.SanityCheckGenericArguments(RuntimeType[] genericArguments, RuntimeType[] genericParamters)
   at System.Reflection.RuntimeMethodInfo.MakeGenericMethod(Type[] methodInstantiation)
   at .š.(Type ‹, MethodBase „†, BindingFlags )
   at .š.(Type ‚, MethodBase „†)
   at ”.“.Create(Object š, MethodInfo ›, Boolean ’)
   at ..(˜ )
   at ..(Expression`1 )
   at Telerik.JustMock.Mock..Ž( )
   at ..—[,—]( , Func`2 )
   at Telerik.JustMock.Mock.Arrange[TResult](Expression`1 expression)

Heres an example of a failing test:

        public void GenericTestCanMockTwoGenericMethods()
            var mocked = Mock.Create<GenericTest>();
            IEnumerable<EVENT_CODE> n = null;
            Mock.Arrange(() => mocked.Query<EVENT_CODE, ALARM_CODE>(Arg.AnyString, Arg.IsAny<object>())).Returns(n).MustBeCalled();

        public interface GenericTest
            IEnumerable<T1> Query<T1, T2>(string arg1, params object[] args);

            IEnumerable<T1> Query<T1, T2, T3>(string arg1, params object[] args);
Last Updated: 22 Nov 2012 15:00 by Philip Japikse
If I have a constructor like this: public Foo(IAccount fromAccount, IAccount toAccount) { //code }, I need to be able to distinguish between the two accounts when automocking.
container.Arrange<IAccount>() won't work.  Perhaps container.Arrange<IAccount>[0] would. 
Last Updated: 04 Nov 2013 15:55 by ADMIN
Created by: Thomas
Comments: 3
Type: Bug Report
I need to be able to mock in Winrt. If that is already possible, then you need to spell out in example form how that is done.
Last Updated: 27 Aug 2013 06:39 by Omer
Created by: Omer
Comments: 0
Type: Bug Report
Hi there, I'm a developer on OzCode, a Visual Studio extension ( ).

We've received some complaints from customers that OzCode is incompatible with JustCode. I installed JustMock, and saw that when Visual Studio starts up, JustMock it seems to be causing a crash in a child process that OzCode spawns off of devenv.exe, which is called 'BugAidMetadataLoader.exe':

The exception in this process is:

Additional information: Could not load type 'Telerik.JustMock.Profiler' from assembly 'mscorlib, Version=, Culture=neutral, PublicKeyToken=b77a5c561934e089'.

I would guess that JustMock is unintentionally causing the process to be loaded with a CLR Profiler attached and injecting code into it, and the injected code causes the crash.

Could you please provide some advice on how to avoid this, or possibly provide a fix?

Thank you very much,
 - Omer Raviv, OzCode
Last Updated: 17 May 2013 12:44 by Jakub
When I try to invoke method from intercepted class in multi-thread test sometimes I get following exception:
Destination array was not long enough. Check destIndex and length, and the array's lower bounds.
   at System.Array.Copy(Array sourceArray, Int32 sourceIndex, Array destinationArray, Int32 destinationIndex, Int32 length, Boolean reliable)
   at System.Array.Copy(Array sourceArray, Int32 sourceIndex, Array destinationArray, Int32 destinationIndex, Int32 length)
   at System.Collections.Generic.List`1.CopyTo(T[] array, Int32 arrayIndex)
   at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
   at System.Linq.Enumerable.ToList(IEnumerable`1 source)
   at Telerik.JustMock.Weaver.ContainerContext.InstanceIdentifier.GetUniqueId(Object target)
   at Telerik.JustMock.Weaver.ContainerContext.Get(Type targetType, MethodBase methodInfo, Object target)
   at Telerik.JustMock.Weaver.ContainerContext.Get(MethodBase methodBase, Object target)
   at Telerik.JustMock.Weaver.Interceptors.WeaverInterceptor.OnInvocation(IInvocation invocation)
   at Telerik.JustMock.Weaver.Interceptors.WeaverInterceptor.Telerik.JustMock.Weaver.Interceptors.Abstraction.IWeaverInterceptor.Intercept(IInvocation invocation)
   at TestClass_Interceptor_620e5e80fe0c4d738f7ef291ea50ea2a.Intercept(TestClass, ref Boolean)
   at ExceptionExample.TestClass.ExecuteSomething() in Test.cs: line 174
   at ExceptionExample.RunMethod() in Test.cs: line 199
   at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
   at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.ThreadHelper.ThreadStart()

Sample class that generates exception:

public class ExceptionExample
	static ExceptionExample()

	public class TestClass
		public void ExecuteSomething()
			int y = 0;
			for (int i = 0; i < 100; i++)
				y += i;

	public void MethodName()
		List<Thread> l = new List<Thread>();

		for (int i = 0; i < 6; i++)
			Thread t = new Thread(RunMethod);

		l.ForEach(th => th.Join());

	private void RunMethod()
		for (int i = 0; i < 10000; i++)
			TestClass tc1 = new TestClass();
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