Postponed Inspection

Scenario

If you are testing whether a device can play an audio file, it is probably easy to verify whether the device reports that it is playing the file, but this does not necessarily mean it is correctly playing it. With a little effort, you could record the device's audio output and check whether or not it is silent. However, to determine whether it is playing the right file, without glitches and with a decent audio quality, is hard.

In this situation, you could decide to implement only the silence check, but then there are a lot of problems your test won't catch. You could also try to develop algorithms for judging the played audio, but this is likely to become a project in itself.

Postponed inspection offers a third option: record the device's audio output and let a human operator listen to it after the test has finished. That way, the entire process of selecting an appropriate device, loading the device with the right software version, selecting the right the file and starting playback is automated and executed during the night, but the judgement whether the audio is correct is done manually.

The tests can run at night while the results are inspected at a moment convenient for the tester; the moments of test execution and result inspection are decoupled.

Solution

Postponed inspection is a way of separating task execution from determining the task result. Because the execution is finished before inspection starts, all resources that were used to execute the task waiting for inspection are free to be used for executing other tasks.

Postponed inspection allows automatic execution of a task even if determining the result cannot be automated. It saves time if the duration of the execution is significant compared to the duration of the inspection.

It should be easy to decide per execution whether postponed inspection is required or not. For example in the scenario outlined above, if you often encounter the situation in which silence is recorded, it is useful to automate the silence check and only ask for postponed inspection if there was actually any sound recorded.