Final answer:
A test driver is a program that verifies function execution correctness, often used in unit testing. It allows developers to identify and resolve errors early in the development process and is integral to software engineering, especially in test-driven development.
Step-by-step explanation:
A test driver is a main program that primarily focuses on verifying that functions execute correctly. It serves as a temporary substitute for a part of a program during the development phase. In practice, a test driver simulates calling a module's or function's interface and passes it test data, checking if the function behaves as expected. This is a crucial part of unit testing, which involves isolating each part of the program and showing that the individual parts are free of errors. Unit testing often requires both test drivers and test stubs, the latter being modules that simulate the behavior of missing components.
Creating test drivers can be a preliminary step before integration testing, which examines the interactions between different units or modules. Effective test drivers enable developers to find and fix errors early in the development cycle, making this form of testing a cornerstone of software engineering principles like test-driven development (TDD).