← Evaluation & Reliability
07 · Evaluation & Reliability · Topic 04

What are Functional Tests?

Functional tests check whether an AI system performs the task it is supposed to perform.

What is it?

A functional test checks whether an AI system produces the required result for a defined task.

It tests behavior that a user or another system can observe. The test can check the answer, format, tool action, refusal, or handling of missing information.

Think of it like...

Think of it like a driving test.

The test gives the driver a known situation and checks the observable result. A functional test checks what the AI system does for a known input.

How it works

1 · DefineChoose the taskState what the system must do.
2 · PrepareSet the inputUse a fixed request and test data.
3 · RunCall the systemRecord the response or action.
4 · CheckCompare the resultCheck the expected behavior or schema.
5 · DecidePass or investigateTrack failures and improve the system.

Real-world examples

Everyday example · Support reply

Input: “How do I reset my password?”

System: returns the approved reset steps.

Output: a helpful answer with no invented policy.

AI product example · Tool call

Input: a request to create a calendar event.

System: calls the calendar tool with the required fields.

Output: a valid event or a clear error.

What it is NOT

Functional Test ≠ Quality Score

Functional test: checks whether a task works.

Quality score: measures how good the result is along a chosen dimension.

Functional Test ≠ Unit Test

Functional test: checks observable system behavior.

Unit test: checks a smaller code component in isolation.

Functional Test ≠ Production Monitoring

Functional test: runs against a planned case.

Production monitoring: watches live behavior after release.

Remember this

A functional test checks whether an AI system does the required job for a defined case.

Independent explainer

Video

visual explainer
↑