Should unit tests cover stress testing?

Question

I am wondering if you guys have any good reading to consider what to classify as unit testing / acceptance / integration testing. I have the following scenario and we're having a bit of a debate at work if it should be in unit tests:

In our data access layer, some statements use sql such as "select * from people where id IN ('x', 'y'), where the IN statement is dynamically generated according to the input. Recently we found out that our Oracle db have a limit of 1000 variables within the IN statement.

I personally think this is not a unit testing scenario. We test if the sql work against the database in unit tests and if the logic is right. However, stress testing should be done at higher level.

If we are to do testing with 1000s of records in unit tests, we need to fill the database each time with large number of records, which might be inefficient.

Any advice?

Answer 1

I believe that stress tests should be implemented as part of unit testing. Generally your unit tests should contain

1. Accuracy tests
2. Failure tests
3. Stress tests

If you don't want to run stress tests each time when you running other tests, you can consider to group stress tests in separate text fixture.

Answer 2

Regarding your particuliar example, you should in fact consider to do 2 tests for it:

• The first one is a Unit Test, and will check that your function can accept the maximum number of input requested by the requirements. If nothing is specified there, ask for clarification to the analyst. Dynamically generated requests such as this are a pain to debug afterward.
• The second one is a Stress test. But it should not be performed onthis particular part of your code, but rather on the integrated part tha will use it. If you start stress testing unit block, you'll end up doing premature optimisation because you'll loose the big picture and start making assumptions on how this will work togetheter rather than observing how it does really.

Answer 3

Unit tests should test, and specify, the functionality of the unit under test. In this case you are testing the database, not the unit, so I think this test is really a unit test.

A unit should be independent of the database it is using, if you are testing the way a unit interacts with a particular database then it seems like an integration test to me