Documentation on testing should mention lack of integrity-related tests in TestCase

[jernej@…]

When using TestCase instead of TransactionTestCase, the documentation mentions that commit and rollback functionality cannot be tested. But as a consequence, since integrity constraints are deferred until a transaction is committed, also integrity errors are not tested when a transaction is simply rolled back after the test. This should probably be explicitly mentioned in the documentation.

[Simon Charette]

We should definitely mention it.

I wonder if it would be possible to SET CONSTRAINTS ALL IMMEDIATE on supported backends.

[Carl Meyer]

I don't think setting constraints to immediate is a good plan; that would just be going from one "differs from production" scenario (constraints not enforced) to another (constraints enforced immediately, thus breaking any code that requires deferred constraints, such as circular FK references). It's not obvious that that's an improvement, therefore IMO we should stick with the simpler behavior (the current behavior).

[Simon Charette]

Replying to carljm:

I don't think setting constraints to immediate is a good plan; that would just be going from one "differs from production" scenario (constraints not enforced) to another (constraints enforced immediately, thus breaking any code that requires deferred constraints, such as circular FK references). It's not obvious that that's an improvement, therefore IMO we should stick with the simpler behavior (the current behavior).

I agree that enforcing constraints on test setup might not a better a option but what about checking them on test tear down just before rolling back the transaction?

[Tim Graham]

Duplicate of #22431