This random behavior beats me

I've already spent a good chunk of the day but get no traction in figuring out this one. In the code below I try to swap a method with another in my test. I'm running this within the VS2010 IDE debugger.

1. if I just run the unit test, I'm getting a TypeMock.ArrangeActAssert.NestedCallException on the Isolate.WhenCalled line that swaps the method.

2. if I debug the unit test and set a breakpoint on the Isolate.WhenCalled line and try to step over I get the same exception. So far so good, although I cannot see where does the nested call come from.

3. here is the best one: I repeat the steps in 2, but before stepping over the Isolate.WhenCalled line I hover over the mock variable and expand it in the debugger's Quick View, no exception happens.

Thank you, eugen


var mock =
Isolate.Fake.Instance<SmartcardService>(Members.CallOriginal,
ConstructorWillBe.Called,
this.workItem);

CancellationToken token = CancellationToken.None;

Isolate.WhenCalled(() =>
mock.ReadCertificates(string.Empty, token)).
DoInstead(callContext =>
{
return ReadTheCertificates((string)callContext.Parameters[0],
(CancellationToken)callContext.Parameters[1]);
});