To test a function, the programmer has to write a _________, which calls the function...

A driver is a piece of code that calls a function or module to be tested and passes it the necessary test data. It is commonly used in bottom-up integration testing to simulate the higher-level modules thatinvoke the function being tested. Stubs, on the other hand, are used to simulate lower-level modules. Reference: ISTQB CTFL Syllabus V4.0, Section 4.3.1​​.