Hi,
You can use the DoInstead API to do that.
DoInstead lets you define your own callback that Isolator will call when the faked method gets called. Inside the callback you have an access to the method arguments and you can check them or modify them.
Here is an example:
public class Foo
{
private void Bar(out int x)
{
x = 1;
}
}
// Test code
var fake = new Foo();
Isolate.NonPublic.WhenCalled(fake, "Bar").DoInstead(context =>
{
context.Parameters[0] = 5;
});
Please let me know if it helps.