Online resources about testing time-dependant code

[intjelic]

I recently discovered property-based testing. It's pretty cool! However, I can't seem to find online resources related to testing pieces of code that involve time.

For example, think of a session API. When a session is consumed, the 'last time used' field must be set to current time. Past a certain time, the session has expired. Etc.

In fact, it's actually a very recurrent need.

Is property-based testing suitable for this use case ? Can anybody point me to online resources that treat this topic?

@ferd Does your book cover this topic ?

[ferd]

One of the key things covered in my book is the importance of having a model-based approach for stateful testing. So what I'd do is define operations such as calls that are within the timeout, and calls that are failing the timeout as if they were distinct operations from the model's point of view.

A wrapper module will stand in between your model (which sees them as deterministic operations) and your real code (which does not), and will either play with time (via mocking) or configured timeouts (successful calls have infinity, failing calls have 0 for a timeout value, for example), to guarantee you get the results you want for each type of operation.

Then the model can check post-conditions such as "if the call succeeded, then I expected to see a time update that is newer than the previous one, but older than now" and so on.