litellm/tests/llm_translation

Unit tests for individual LLM providers.

Name of the test file is the name of the LLM provider - e.g. test_openai.py is for OpenAI.

Redis-backed VCR cache

Every test in this directory is auto-decorated with @pytest.mark.vcr (via conftest.py). The first time a test runs we hit the live provider and record the HTTP exchange into Redis under litellm:vcr:cassette:<test_id>. Every subsequent run within 24h replays from Redis without touching the network. The 24h TTL means each new day's first run records again, so upstream API drift surfaces within a day.

The persister, header scrubbing, and 2xx-only filtering are defined in tests/_vcr_redis_persister.py. Files that already use respx (which patches the same httpx transport vcrpy does) are excluded from the auto-marker — see _RESPX_CONFLICTING_FILES in conftest.py.

The same VCR cache is used by other test directories that exercise live provider APIs. The reusable conftest plumbing lives in tests/_vcr_conftest_common.py and is wired into:

• tests/llm_translation/
• tests/llm_responses_api_testing/
• tests/audio_tests/
• tests/batches_tests/
• tests/guardrails_tests/
• tests/image_gen_tests/
• tests/litellm_utils_tests/
• tests/local_testing/ (covers local_testing_part1, local_testing_part2, litellm_router_testing, litellm_assistants_api_testing, langfuse_logging_unit_tests)
• tests/logging_callback_tests/
• tests/pass_through_unit_tests/
• tests/router_unit_tests/
• tests/unified_google_tests/

Test directories that run LiteLLM proxy in Docker (e.g. build_and_test, proxy_logging_guardrails_model_info_tests, proxy_store_model_in_db_tests) are intentionally not included: VCR.py patches the in-process httpx transport, so it cannot intercept the LLM calls that originate inside the Docker container.

Required environment

CASSETTE_REDIS_URL — separate Redis instance from the application Redis (REDIS_URL/REDIS_HOST) so test cassettes are not flushed by proxy tests. Provider credentials (ANTHROPIC_API_KEY, OPENAI_API_KEY, AWS_*, etc.) are needed only on cache-miss (the daily re-record), not on replay.

Flushing the cache

When you want the next run to re-record immediately instead of waiting for the 24h TTL:

make test-llm-translation-flush-vcr-cache

Disabling VCR

Skip the cache entirely (every call goes live, no recording):

LITELLM_VCR_DISABLE=1 uv run pytest tests/llm_translation/test_<file>.py