ADR 0007: pytest fixture as the primary developer experience

• Status: Accepted

Context

The primary user for bqemulator is a developer writing tests. Forcing users to start a separate process, wire an env var, and manage lifecycle is friction.

Decision

Ship a pytest plugin via the pytest11 entry point in pyproject.toml. pip install bqemulator makes bqemu_server, bqemu_endpoint, and bqemu_client fixtures available automatically with zero conftest.py setup.

The fixture runs the emulator in-process on a background thread with its own asyncio event loop (see bqemulator.testing._thread_runner), so synchronous test code and the Google Python client can use it naturally.

Consequences

• Positive: friction-free DX; users pip install and start writing tests.
• Positive: ephemeral mode means every test session starts clean.
• Negative: threading the event loop adds some complexity. Encapsulated in the plugin; users never see it.