Cannot create FunctionFailedException in unit test

[DarranShepherd]

I am creating unit tests for my orchestrator function, following the guidance on https://docs.microsoft.com/en-us/azure/azure-functions/durable/durable-functions-unit-testing .

I wish to test the logic that handles one of my activity tasks throwing an exception. The orchestrator handles this with

catch (FunctionFailedException ex) when (ex.InnerException is MyCustomException)

However, I am unable to mock the call to CallActivityAsync and have it throw as all constructors of FunctionFailedException are internal. As Exception.InnerException is not virtual, I also cannot use Mock.Of<FunctionFailedException>(ex => ex.InnerException == new MyCustomException())

I have been able to resolve this temporarily by using reflection, but I doubt this is the expected approach. Is this not something that should be tested for some reason, or is there an official way to do so?

private FunctionFailedException CreateException(string message, Exception inner)
{
    var ctor = typeof(FunctionFailedException).GetConstructor(BindingFlags.NonPublic | BindingFlags.Instance, null, new[] { typeof(string), typeof(Exception) }, null);
    return (FunctionFailedException)ctor.Invoke(new object[] { message, inner });
}

[cgillum]

I think it makes sense for us to expose those constructors to make things more unit testable. @ConnorMcMahon what do you think?

[cgillum]

This fix was released as part of v1.8.2.