To replicate the problem using the provided project, follow these steps:

1. Open the solution in Rider.
2. Set breakpoints at the beginning of the test.
3. Start debugging the test.
4. Step into the constructor of the Car class and inspect the contents of the array. Note that if this step is skipped, the issue will not be reproducible.
5. Step out of the constructor.
6. Continue execution until just before calling the virtual function for the Number property.
7. Step into the function.

**EXPECTED** The value of Name should be visible.

**ACTUAL** A debugger error occurs.

The issue can appear in both Visual Studio (showing "Internal error in the C# compiler") and Rider (showing "Read out of bounds"). 

My setup includes my local dev environment and so called "grid node" server used by NCrunch.

Yesterday I've updated JustMock to version 2025.2.520.440.
After that update I received an error mentioning my License file not to include Telerik Just Mock.
So I've updated my License file by the way mentioned in the Release Notes.

After that my NCrunch Build crashed with an TypeInitializationException "The type initializer for 'Telerik.JustMock.Core.Licensing.LicenseManager'. String was not recognized as a valid DateTime."

I've updated my License file again today and the Exception Message has changed to "String '5/20/2025' was not recognized as a valid DateTime."

I than set my local DateDime format from dd.MM.yyyy to yyyy-MM-dd and the problem is gone.
So it seems like the current version has a problem with our German / European format.

With version 2025.1.211.365 everything worked fine.

So would you please so kind to have a look onto that?
Thank you

We're using this DevOps task in our pipeline, however since yesterday we get the following warning:

##[warning]Task 'Telerik JustMock VSTest v.2' version 2 (JustMockVSTest@2) is dependent on a Node version (6) that is end-of-life. Contact the extension owner for an updated version of the task. Task maintainers should review Node upgrade guidance: https://aka.ms/node-runner-guidance

We're running it using a build agent hosted at the Azure DevOps cloud.

Having the simple class

public class MyClass
{
    public event Func<EventArgs, Task>? MyEventAsync;
}

and the test that tries to rise the declared event

[TestMethod]
public void TestMethod1()
{
    var mockClass = Mock.Create<MyClass>(Behavior.Strict);
    mockClass.MyEventAsync += (args) => Task.CompletedTask;

    Mock.Raise(() => mockClass.MyEventAsync += null, EventArgs.Empty);
}

Execution triggers the following error:

Telerik.JustMock.Core.MockException : Event signature System.Threading.Tasks.Task OnMyEventAsync(System.EventArgs) is incompatible with argument types (Castle.Proxies.ExternalMockMixinProxy, System.EventArgs)

which is kind of unexpected since the supplied arguments are matching to the event's signature.

With R3 2023 (2023.3.1011.155) JustMock introduces a new functionality that might lead to a huge performance drop and event to unexpected failures. Currently, the issue could be suppressed by setting up an environment variable JUSTMOCK_NEWOBJ_INTERCEPTION_ON_OVERWRITE_ENABLED to 0 (the default value is 1), but a more reliable and independent solution should be found.

The issue is about interoperability between JustMock and AutoFixture. The unit test run can be 90% faster if all the fixtures are created before the JustMock arrangements.

Here is a sample code that figures out the issue:

[Fact]
public void Slow
{ 
    var fixture = new Fixture():

    var items1 = fixture.Create<List<Item>>();
    Nock.Arrange(() => ItemsRepository.GetItems1()).Returns(items1);

    var items2 = fixture.Create<List<Item>>();
    Nock.Arrange(() => ItemsRepository.GetItems2()).Returns(items2);

    var items3 = fixture.Create<List<Item>>();
    Nock.Arrange(() => ItemsRepository.GetItems3()).Returns(items3);

    var items4 = fixture.Create<List<Item>>();
    Nock.Arrange(() => ItemsRepository.GetItems4()).Returns(items4);
}

[Fact]
public void Fast()
{
    var fixture = new Fixture():

    var items1 = fixture.Create<List<Item>>();
    var items2 = fixture.Create<List<Item>>();
    var items3 = fixture.Create<List<Item>>();
    var items4 = fixture.Create<List<Item>>();

    Nock.Arrange(() => ItemsRepository.GetItems1()).Returns(items1);
    Nock.Arrange(() => ItemsRepository.GetItems2()).Returns(items2);
    Nock.Arrange(() => ItemsRepository.GetItems3()).Returns(items3);
    Nock.Arrange(() => ItemsRepository.GetItems4()).Returns(items4);
}

The test duration should not be dependent on the exact implementation.

Dear Telerik team,
It is nice to have a way to generate mocks.

But it is annoying to have lots of those messages for references in XML comments. I had to turn the feature off. Which might be the case for other customers too.

Maybe you want to have a look into it.

I am unable to mock interfaces that contain a method with an `in` parameter. When running the following code snippet, the result is an exception:

Message: 
  Test method Example.UnitTests.UnitTest.TestMethod threw exception:
  Telerik.JustMock.Core.MockException: Abstract type 'Example.UnitTests.InParamExample' is not accessible for inheritance.

Stack Trace: 
  MocksRepository.Create(Type type, MockCreationSettings settings)
  <>c__38`1.<Create>b__38_0()
  ProfilerInterceptor.GuardInternal[T](Func`1 guardedAction)
  UnitTest.TestMethod() line 23

namespace Example.UnitTests
{
    using Microsoft.VisualStudio.TestTools.UnitTesting;
    using Telerik.JustMock;

    public interface ParamExample
    {
        void Foo(int param);
    }

    public interface InParamExample
    {
        void Foo(in int param);
    }

    [TestClass]
    public class UnitTest
    {
        [TestMethod]
        public void TestMethod()
        {
            var mockedParamExample = Mock.Create<ParamExample>();
            var mockedInParamExample = Mock.Create<InParamExample>();
        }
    }
}

The following code snippet causes a hang in the test execution while being debugged:

Mock.SetupStatic(typeof(TimeSpan), Behavior.CallOriginal, StaticConstructor.NonMocked);
Mock.Arrange(() => TimeSpan.FromSeconds(15)).Returns(TimeSpan.MinValue);

The issue can be temporary solved by disabling the DebugWindow via JustMock extension menu. 

Hello

I generate a syntax tree which I will format with Formatter.Format() from the package Microsoft.CodeAnalysis.CSharp.Workspaces 4.4.0 and .NET 6. A test exists where the formatter is used but when the JustMock profiler is enabled an InvalidProgramException is thrown. When the profiler is disabled everything works fine. It fails on Windows and on Linux.

Exception

  Message: 
System.InvalidProgramException : Common Language Runtime detected an invalid program.

  Stack Trace: 
ContextIntervalTree`2.ctor(TIntrospector& introspector)
FormattingContext.ctor(AbstractFormatEngine engine, TokenStream tokenStream)
AbstractFormatEngine.CreateFormattingContext(TokenStream tokenStream, CancellationToken cancellationToken)
AbstractFormatEngine.Format(CancellationToken cancellationToken)
CSharpSyntaxFormatting.Format(SyntaxNode node, SyntaxFormattingOptions options, IEnumerable`1 formattingRules, SyntaxToken startToken, SyntaxToken endToken, CancellationToken cancellationToken)
AbstractSyntaxFormatting.GetFormattingResult(SyntaxNode node, IEnumerable`1 spans, SyntaxFormattingOptions options, IEnumerable`1 rules, CancellationToken cancellationToken)
Formatter.GetFormattingResult(SyntaxNode node, IEnumerable`1 spans, Workspace workspace, OptionSet options, IEnumerable`1 rules, CancellationToken cancellationToken)
Formatter.Format(SyntaxNode node, IEnumerable`1 spans, Workspace workspace, OptionSet options, IEnumerable`1 rules, CancellationToken cancellationToken)
Formatter.Format(SyntaxNode node, Workspace workspace, OptionSet options, CancellationToken cancellationToken)
UnitTest1.Test1() line 23

Reproduction

You can reproduce this by writing an unit test for that (I used xUnit):

        [Fact]
        public void Test1()
        {
            var classText = @"using System; namespace TestNameSpace.Orders { public class Order
                            {
                                public Guid Id { get; set; }
                            }
                        }";

            var syntaxTree = CSharpSyntaxTree.ParseText(classText);
            var workspace = new AdhocWorkspace();

            var formattedClassText = Formatter.Format(syntaxTree.GetRoot(), workspace).ToFullString();

            var expected = @"using System;
namespace TestNameSpace.Orders
{
    public class Order
    {
        public Guid Id { get; set; }
    }
}";
            Assert.Equal(expected, formattedClassText);
        }
    }

System Info

JustMock

See attachments. We do not use the free edition.

.NET

dotnet --info
.NET SDK:
 Version:   7.0.200
 Commit:    534117727b

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.19045
 OS Platform: Windows
 RID:         win10-x64
 Base Path:   C:\Program Files\dotnet\sdk\7.0.200\

Host:
  Version:      7.0.3
  Architecture: x64
  Commit:       0a2bda10e8

.NET SDKs installed:
  6.0.406 [C:\Program Files\dotnet\sdk]
  7.0.200 [C:\Program Files\dotnet\sdk]

.NET runtimes installed:
  Microsoft.AspNetCore.App 6.0.14 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 7.0.3 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 6.0.14 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 7.0.3 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.WindowsDesktop.App 6.0.14 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 7.0.3 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

Other architectures found:
  x86   [C:\Program Files (x86)\dotnet]
    registered at [HKLM\SOFTWARE\dotnet\Setup\InstalledVersions\x86\InstallLocation]

Environment variables:
  Not set

global.json file:
  Not found

Learn more:
  https://aka.ms/dotnet/info

Download .NET:
  https://aka.ms/dotnet/download

 

Considering the following simple test scenario:

public abstract class TestBase
{
    public static TestContext TestContext { get; set; }
}

[TestClass]
public class UnitTest1 : TestBase
{
    [ClassInitialize]
    public static void ClassInitlialize(TestContext ctx)
    {
        TestContext = ctx;
    }

    [TestMethod]
    public void TestMethod1()
    {

    }
}

[TestClass]
public class UnitTest2 : TestBase
{
    [ClassInitialize]
    public static void ClassInitlialize(TestContext ctx)
    {
        TestContext = ctx;
    }

    [TestMethod]
    public void TestMethod1()
    {

    }
}

Attempt to run the tests above with JustMock profiler enabled fails with System.InvalidProgramException. The issue is not reproducible with MSTest.TestFramework and MSTest.TestAdapter packages prior to 3.0.x.

The issue is demonstrated with the following sample:

[Theory]
[MemberData(nameof(GetMemberDataContext))]
public void ValidParameters_Success(int param1, int param2)
{
	// Arrange
	Mock.SetupStatic(typeof(MyClass), Behavior.Strict, StaticConstructor.Mocked);
        Mock.Arrange(() => MyClass.method1()).Returns(true);

        // Act
	IService service = new Service();
	bool result = service.method2();

	// Assert
	Assert.True(result);
	Mock.Assert(() => MyClass.method1(), Occurs.Once()); // <-- the test fails here because it reports that method invocation occurs twice
}

The issue in not observed if the code is modified in the following way, which indicates behavioral incinsistency:

[Theory]
[MemberData(nameof(GetMemberDataContext))]
public void ValidParameters_Success(int param1, int param2)
{
	// Arrange
	Mock.SetupStatic(typeof(MyClass), Behavior.Strict, StaticConstructor.Mocked);
        Mock.Arrange(() => MyClass.method1()).Returns(true).OccursOnce();

        // Act
	IService service = new Service();
	bool result = service.method2();

	// Assert
	Assert.True(result);
	Mock.Assert<MyClass>();
}

if you use the C# using declaration and have JustMock advanced (elevated) mode enabled, the runtime will throw an InvalidProgramException.

Find below the sample code that demonstrates the issue:

public class TestClass : IDisposable
{
    public void Dispose()
    {
    }
}

[TestClass]
public class Fixture
{
    public interface ITest { }

    [TestMethod]
    public async Task Test()
    {
        ITest mock = Mock.Create<ITest>();
        using TestClass test = new();
    }
}

There are older releases with a version of 1.0.0.4 for the Telerik.JustMock.Console.exe and with the R3 2022 release, the version is 1.0.0.3.

A unit test run against a simple class using EntityFramework never completes, here's the code:

public class DbContext1 : DbContext
{
    public DbContext1(string connectionString)
    {
    }
}

public class Program
{
    private static readonly SemaphoreSlim _lock = new SemaphoreSlim(1, 1);

    public async Task Run()
    {
        await _lock.WaitAsync();
        try
        {
            await InsertDbRow();
        }
        finally
        {
            _lock.Release();
        }
    }

    private static async Task InsertDbRow()
    {
        await RetryWrapperAsync(async () =>
        {
            using DbContext1 dbContext = new DbContext1("con str");
            await dbContext.SaveChangesAsync();
        });
    }

    public static async Task RetryWrapperAsync(Func<Task> operation)
    {
        for (int i = 0; i < 3; i++)
        {
            try
            {
                await operation();
                break;
            }
            catch (Exception)
            {
                await Task.Delay(100);
            }
        };
    }
}

[TestClass]
public class ProgramTest
{
    private readonly DbContext1 mockContext1 = Mock.Create<DbContext1>();

    [TestInitialize]
    public void SetUp()
    {
        Mock.Arrange(() => new DbContext1("con str")).Returns(mockContext1);
    }

    [TestMethod]
    public async Task TestMethod()
    {
        // Arrange
        Program program = new Program();

        // Act
        await program.Run(); // <-- at this point the test hangs
    }
}

Adding do-nothing arrangement on mockContext.SaveChanges fixes the hang, but the expectation is that mock will handle this case by default and there is no need to be explicitly arranged.

Referencing the nuget Microsoft.ApplicationInsights.AspNetCore V2.20.0 in the project that is tested leads to the VS 2019 code coverage failing to produce the report. Here are the steps to reproduce:

1. Create a project from the template ASP.NET Core Web API targeting .NET 5

2. Add a reference to the nuget package Microsoft.ApplicationInsights.AspNetCore V2.20.0

3. Create a unit test project from the C# JustMock Test Project (.NET Core) template.

4. Run the VS code coverage.

Expected result: the code coverage report is produced.

Actual result: there is no code coverage report

Using the mentioned (or later) product version, the following simple test fails (throws NullReferenceException):

[TestMethod]
public void TestMethod()
{
    var cultureInfo = Mock.Create<CultureInfo>();
    var thisThrowsAnException = cultureInfo.Name;
}

One of the possible workarounds is to create a mock like this:

readonly string cultureName = CultureInfo.InvariantCulture.Name;
...
var cultureInfo = Mock.Create(() => new CultureInfo(cultureName));