* fix(tests): stop VCR recording and replaying a test's own localhost upstream * test(vcr): prove a localhost response an earlier run stored is never replayed * test(vcr): drive the localhost cassette checks in-process instead of through a loopback server --------- Co-authored-by: mateo-berri <277851410+mateo-berri@users.noreply.github.com>
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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/(coverslocal_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