upstream-zulip/.claude/rules/testing.md

paths

paths
zerver/tests/** zerver/webhooks/** web/tests/**

Testing Philosophy

• Write end-to-end tests when possible verifying what's important, not internal APIs.
• Tests must work offline. Use fixtures (in zerver/tests/fixtures) for external service testing and responses for simpler things.
• Use time_machine and similar libraries to mock time.
• Read zerver/tests/test_example.py for patterns.
• A good failing test before implementing is good practice so your test and code can jointly verify each other.
• Remember to always assert state is correctly updated, not just "success".
• In tests, don't assert on assertLogs output with any(phrase in line for line in mock_log.output); pin the full line against mock_log.output, or a substring to a specific mock_log.output[i].

A common failure mode is failing to have test coverage for error conditions that require coverage (note tools/coveragerc excludes asserts). Run test-backend --coverage FooTest and check the coverage data to confirm that the new lines you added are in fact run by the tests.

For webhooks

./tools/test-backend zerver/webhooks/<integration>