Test Fixture Data Management

APPEND TO RULE:

behave AT: Background + scenario idempotency

Applies to acceptance tests (docs/features/) using behave-django, not only E2E preset JSON.

When Background: loads or seeds entities and a scenario Given creates the same logical record (same slug, username, or other natural unique key):

• Use get_or_create / update-in-place in the step definition.
• Prefer factory django_get_or_create on stable keys when using FactoryBoy in Givens.
• Treat IntegrityError during AT as a fixture contract bug until proven otherwise.

Reference: Skill 45 Pattern 5; TFK-04 Build Fixture Library activity.