I have to disagree with you. This is a perfectly reasonable request. In fact, this is considered a good practice for testing complex software.

There are lots of reasons for doing things like this:

1. You may not have control over function y
2. It might do something that you don't want to do during testing (such as submit a credit card order...)
3. It might take a long time to run.
4. It might be hard to reproduce certain kinds of output.
5. It might not be written yet, or it might have bugs of its own (simulating part of the software allows you to develop/test multiple interdependent pieces of code simultaneously).

Thanks for the reasons. I normally suppress things I don't want to do during a test run, but I can see your points :-)
A Monk aims to give answers to those who have none, and to learn from those who know more.

Obviously, changing function calls at run time is not the only way to overcome the above problems. The important thing is using good testing principles, rather than a particular implementation.

I think it is a useful and powerful tool for certain kinds of testing.



When's the last time you used duct tape on a duct? --Larry Wall