High-level test case: A high-level test case is defined as a test case without concrete values for input data and expected results.
- Logical operators are used; instances of the actual values are not yet defined and/ or available.
- For example, input age with any value > 50 and expect an error message.
Low-level test case: A low-level test case is defined as a test case with concrete values for input data and expected results.
- Logical operators from high-level test cases are replaced by actual values that correspond to the objectives of the logical operators.
- For example, input age = 65 and expect an error message “sorry, the age value should be between 20 and 50.”
- Low-level test cases provide all the specific information and procedures needed for the tester to execute the test case (including any data requirements) and verify the results.
Advantages of using Low-level test cases are:
- Anyone can run the tests
- Excellent reproducibility tests
- Enable external verification of the tests, such as audits.
- Non-obvious defects in the test basis can be revealed.
- Time spent on automated test case implementation can be reduced.
Disadvantages of using Low-level test cases are :
- May require a significant amount of effort, both for creation and maintenance.
- Tends to limit tester creativity during execution.
- Requires the test basis be well defined.
- Traceability to test conditions may take more effort than with high-level test cases.
Advantages of using high-level test cases are:
- Give guidelines for what should be tested and allow the Test Analyst to vary the actual data or even vary the executed procedure when executing the test.
- Can be defined early in the requirements process.
- Make use of the Test Analyst’s experience with both testing and the test object when the test is executed.
- Can be defined when no detailed and formal documentation is required.
- Better suited for reuse in different test cycles when different test data can be used.
- Creating high-level tests is cheaper than creating low-level tests as high-level tests are much smaller in size and number and require less time than creating low-level test cases.
- High-level test cases may provide better coverage than low-level test cases because they will vary somewhat each time they are executed.
Disadvantages of high-level test cases are:
- Less reproducible, making verification difficult.
- More experienced testing staff may be needed to execute them
- When automating based on high-level test cases, the lack of details may validate the wrong outcomes or missing items that should be validated.