What is test driver and test stub?

- The Stub is called from the software component to be tested. It is used in top down approach.
- The driver calls a component to be tested. It is used in bottom up approach.
- Both test stub and test driver are dummy software components.

We need test stub and test driver because of following reason:

- Suppose we want to test the interface between modules A and B and we have developed only module A. So we cannot test module A but if a dummy module is prepare, using that we can test module A.

- Now module B cannot send or receive data from module A directly so, in these cases we have to transfer data from one module to another module by some external features. This external feature used is called Driver.