In my project, I use pytest to write unit test cases for my program. But later I find I there are many db operation, ORM stuff in my program.
I known unit-testing should be run fast, but what is the different between unit-testing and auto integration-testing except fast.
Should I just use the database fixture instead of mocking them?
The main difference between unit tests and integration tests are that integration testing deal with the interactions between two or more "units". As in, a unit test doesn't particularly care what happens with the code surrounding it, just as long as the code within the unit test operates as it's designed to.
As for your second question, if you feel the database and fixtures in your unit test suite is taking too long to run, mocking is a great solution.
Django testing method, fixture or mock?