improving performance of django tests with nested transactions/savepoints
This monkey-patches django.tests.testcases.TestCase so that all tests in a TestCase take place in a BEGIN transaction, while test methods take place in a nested transaction, with a savepoint being recorded after fixtures are loaded before a test, and rolling back to it after the test completes.
Although previously I suggested memoizing yaml loading, we still would have to execute database insertions for fixtures; this method minimizes it to a per-TestCase level, instead of per-test method.
Note that this will only have a significant impact if your tests use fixtures, but when it does, it'll blow your socks off.
For a simple benchmark, I'll be using satchmo's satchmo_store.shop.tests. It has 9 test cases, with the bulk in two of them - 20 tests in one, and 14 in the other. The former also uses Client, another major performance hog. Both use fixtures.
I'll also be using django 1.2, with nested transaction support for sqlite3.
Here are the numbers:
- 65.013s: no optimizations applied
- 61.904s: memoized yaml
- 47.229s: nested transactions in TestCase
- 43:917s: nested transactions in TestCase, memoized yaml
