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.

Requests to localhost, 127.0.0.1, or 0.0.0.0 are never recorded or replayed (ignore_localhost in vcr_config_dict()): a server the test process starts itself on an ephemeral port is not a provider, and a cassette entry for it would replay against whichever later test lands on that port

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