C# 8 introduces default interface method implementations. Attempt to mock such methods with JustMock in elevated mode fails. The following example illustrates the issue:

public interface IMyInterface
{
    int IntProperty { get => 0; }
}


[TestClass]
public class UnitTest1
{
    [TestMethod]
    public void TestMethod1()
    {
        var mock = Mock.Create<IMyInterface>();
        Mock.Arrange(() => mock.IntProperty).Returns(1);

        Assert.AreEqual(1, mock.IntProperty);
    }
}

Attempt to use JustMock VSTest v.2 task to run the elevated mode tests with coverage when the "Test platform version" option is set to value "Installed by Tools Installer" fails with error:

Telerik.JustMock.Core.ElevatedMockingException: Cannot mock '<target type goes here>'. The profiler must be enabled to mock, arrange or execute the specified target.
Detected active third-party profilers:
* {9317ae81-bcd8-47b7-aaa1-a28062e41c71} (from process environment)
Disable the profilers or link them from the JustMock configuration utility. Restart the test runner and, if necessary, Visual Studio after linking.

Currently, when the JustMock profiler is enabled it provides a performance hit on the test execution. This effect is expected because a profiler is involved.

What we can do is find a more optimized way of instrumenting the methods.

The internal (non-public) events are not handled properly by JustMock, there is no indication for error, Raise arrangement simply does not working as expected. The following sample reproduces the issue:

namespace TestExample
{
    public class ClassWithEvents
    {
        internal event EventHandler<EventArgs> InternalEventToTest;
    }

    [TestClass()]
    public class EventTests
    {
        [TestMethod]
        public void ClassWithEvents_InternalEventTest()
        {
            //Arrange
            bool eventRaised = false;
            ClassWithEvents classWithEvents = Mock.Create<ClassWithEvents>();
            classWithEvents.InternalEventToTest += (object sender, EventArgs e) =>
            {
                eventRaised = true;
            };

            // Act
            Mock.Raise(() => classWithEvents.InternalEventToTest += null, new EventArgs());

            // Assert
            Assert.IsTrue(eventRaised);
        }
    }
}

The test run is aborted when a .testsettings is used for executing JustMock tests. The .testsettings contains only a description.

<?xml version="1.0" encoding="UTF-8"?>
<TestSettings name="Local" id="15694c75-be1c-4113-9d42-2cbe1013c41c" xmlns="http://microsoft.com/schemas/VisualStudio/TeamTest/2010">
  <Description>These are default test settings for a local test run.</Description>
</TestSettings>

It seems that the usage of the MSTest element is breaking the execution. As .testsettings are deprecated use .runsettings instead without MSTest element.

I am unable to debug my unit test .NET project. I keep getting several of these errors, and it is super slow as code tries to execute every line. I have rebooted and restarted VS 2019 several times, reinstalled JustMock but the error won't go away.

Visual Studio Output windows shows following repeated errors:

Exception thrown calling IDebugWindowPlugin plugin: System.NullReferenceException: Object reference not set to an instance of an object.

I have a class, which has a private async method, which has a local function, like the following example

internal class TestClass

{

 ......

        private async Task<bool> TestPrivateMethod()
        {
            var x = await TestLocalFunction();
            return x;

            async Task<bool> TestLocalFunction()
            {
                await Task.Delay(5);
                return true;
            }
 }

When I try to mock the local function, thows an error "System.MissingMemberException : C# 7 local function 'TestLocalFunction' with the given signature was not found inside method 'TestPrivateMethod'"

var testClassInstance = Mock.Create<TestClass>(Behavior.CallOriginal);

Mock.Local.Function.Arrange<Task<bool>>(testClassInstance, "TestPrivateMethod", "TestLocalFunction").Returns(Task.FromResult(true));

Having the following COM interop class

[ClassInterface(ClassInterfaceType.None)]
[Guid("86332C4E-0BDE-46EC-94C5-0A946C33C682")]
[TypeLibType(TypeLibTypeFlags.FCanCreate)]
public class MyComObjectClass : IMyComObject, MyComObject
{
    public MyComObjectClass();

    [DispId(1)]
    public virtual string Echo(string message);
}

and the sample class that uses it:
public class MyComObjectClassProxy
{
    public string Echo(string message)
    {
        IMyComObject itf = null;
        try
        {
            itf = new MyComObjectClass();
            return itf.Echo(message);
        }
        finally
        {
            if (itf != null)
            {
                Marshal.ReleaseComObject(itf);
            }
        }
    }
}
When I try to call the arranged constructor I am getting an error "Cannot create instances of type requiring managed activation", the unit test code:
[TestMethod]
public void TestMethod1()
{
    var mock = Mock.Create<MyComObjectClass>();
    Mock.Arrange(() => new MyComObjectClass()).Returns(mock);

    var sut = new MyComObjectClassProxy();
    var actual = sut.Echo("Message");

    Assert.AreEqual(string.Empty, actual);
}

When a breakpoint is added inside an async test that uses JustMock the debugger is failing to hit it. 

To reproduce the issue follow the next steps:

1. Open the attached project

2. Create a breakpoint at the first arrangement in the async test method.

3. Start debugging the async test

Result: the breakpoint is not hit.

The issue is observed for both .NET Core and .NET Framework.

Integration with Visual Studio Enterprise Code Coverage does not work if the project refers Microsoft.NET.Test.Sdk package version 16.3 (and above). The test run fails with exception:

Telerik.JustMock.Core.ElevatedMockingException : Cannot mock '<type to mock goes here>'. The profiler must be enabled to mock, arrange or execute the specified target.
    Detected active third-party profilers:
    * C:\Program Files (x86)\Microsoft Visual Studio\2019\Enterprise\Team Tools\Dynamic Code Coverage Tools\amd64\covrun64.dll (from process environment)
    Disable the profilers or link them from the JustMock configuration utility. Restart the test runner and, if necessary, Visual Studio after linking.