Glossary · Verification and validation
Functional test
Also known as: function test
In verification and validation, a functional test is a test that confirms required behavior under defined normal and fault conditions. For safety functions, it checks that the specified trigger leads to the specified reaction within the specified time.
- Verification
- Functional safety
In one sentence
A functional test confirms that a function behaves as required under defined normal and fault conditions, with recorded criteria and results.
Example
At commissioning of a conveyor line, each emergency stop button is pressed in turn and the tester confirms that the correct zones stop, the restart is blocked and a reset is required.
How it applies
- Verification: Define the test conditions, steps, expected results and acceptance criteria before testing. A test without a pass criterion is an observation, not evidence.
- Functional safety: Include fault conditions, not only the normal case. Fault injection is a common way to create them.
- Technical documentation: Tests that users must repeat, such as a daily check of an emergency stop, belong in the operating manual with clear steps and a record form.
- Evidence: Record software versions, configuration, instruments and tester for each test, so that the result can be tied to the exact state of the machine.
Functional test vs. validation
A functional test checks one function against its requirement. Validation uses many such tests, plus analysis and review, to confirm that the safety solution as a whole fits its intended use.