๐ค Complete Guide to Test Harness Components | ๐ Includes Practice Questions for Information Processing Engineer Exam
Summary
A comprehensive guide to the components of a test harness (Test Driver, Stub, Suite, Case, Scenario, Script, Mock Object), a key concept for the Information Processing Engineer practical exam. It clearly explains the difference between Test Drivers and Stubs, which are frequently tested.
๐ก Questions about the roles and differences between Test Driver and Test Stub are common in the Information Processing Engineer practical exam. Clearly distinguishing and memorizing these two concepts is key to passing.
โ๏ธ What is a Test Harness?
A Test Harness refers to a software tool or framework that builds an environment for executing tests in unit or module testing. It can be described as an execution environment that bundles code and data to support testing, ensuring that the component under test functions correctly.
Its main components include Test Drivers, Test Stubs, Test Suites, and Test Cases, which together form a single test environment.
1. Core Components of a Test Harness
Test Driver
A Test Driver is test code that acts as a high-level module to call the module under test and verify the test results. It is primarily used in Bottom-up testing.
- Role: Calls the lower-level module (the one being tested) to start the test, passes parameters, and checks the results.
- Direction:
High-level Module โ [Test Driver]+Low-level Module (Under Test) - Keywords: Bottom-up testing, low-level module testing, calling module
Test Stub
A Test Stub is a dummy module that temporarily replaces the functionality of another module called by the module under test. It is primarily used in Top-down testing.
- Role: Temporarily performs the role of a lower-level module called by the high-level module (under test), returning pre-defined values or handling simple logic.
- Direction:
High-level Module (Under Test)+Low-level Module โ [Test Stub] - Keywords: Top-down testing, high-level module testing, called module
๐ก [Exam Tip] Perfect Comparison: Test Driver vs. Test Stub
This table perfectly summarizes the two concepts.
| Category | Test Driver | Test Stub |
|---|---|---|
| Purpose | Used to test a low-level module | Used to test a high-level module |
| Role | Acts as a high-level module that calls the UUT | Acts as a low-level module that is called by the UUT |
| Testing | Bottom-up testing | Top-down testing |
| Analogy | A driver operating a car | A stunt double (Stub) standing in for the main actor |
| Flow | Driver โ UUT (Low-level) | UUT (High-level) โ Stub |
Other Key Components
| Component | Description |
|---|---|
| Test Suite | A collection of test cases. A unit that groups all test cases for a specific feature or module. |
| Test Case | A specification of inputs, execution conditions, and expected results to verify a specific requirement. The smallest unit of a test. |
| Test Scenario | A validation of a single workflow (story) by grouping multiple test cases. (e.g., 'Log in and then write a post') |
| Test Script | Code written to execute test cases in an automated fashion. |
| Mock Object | Similar to a stub, but a more sophisticated object that also verifies the state or behavior of calls. (e.g., 'Was method A called 3 times?') |
๐ Practice Questions for the Exam
| Problem | In bottom-up unit testing, what is the test harness component that acts as a high-level module to call the low-level module under test, pass parameters, and execute the test? |
| Your Answer | |
| Correct Answer | Reveal Answer |
| Problem | In top-down unit testing, what is the dummy module that temporarily replaces the functionality of a low-level module called by the high-level module under test? |
| Your Answer | |
| Correct Answer | Reveal Answer |
| Problem | What is the term for a set of inputs, execution conditions, and expected results for a test, representing the smallest unit of testing? |
| Your Answer | |
| Correct Answer | Reveal Answer |