llmentary

Python (pytest) client for llmentary: deterministic trace-based integration tests for LLM apps.

llmentary is the Python/pytest client for the barzoj-co/llmentary recording proxy. See Versions for __version__, proxy_version(), and python -m llmentary --version. It gives tests deterministic, trace-based assertions for OpenAI-compatible Chat Completions and Responses calls. There is no LLM judge: assertions inspect the requests, responses, tool calls, usage, timings, retries, and errors the proxy recorded. The control API contract (GET {control}/openapi.yaml) describes /healthz, /sessions, and /sessions/{id}/wait. Platform wheels bundle the same openapi.yaml next to the proxy binary. ControlClient.openapi() returns the served document; contract_path() is the bundled file.

Published platform wheels bundle proxy v0.4.1; see docs/binaries.md for how it is resolved and how to override it.

Install

pip install llmentary

Platform wheels bundle the version-pinned proxy binary (PROXY_VERSION, currently 0.4.1). The sdist is client-only and does not include a binary. Install a wheel with pip install --only-binary=:all: llmentary, or set LLMENTARY_BIN, or put llmentary on PATH. There is no llmentary console script (that name is the proxy binary). Run python -m llmentary doctor to see what this install resolved, or python -m llmentary --version for the client and proxy versions.

Supported wheel tags: manylinux2014_x86_64, manylinux2014_aarch64, macosx_11_0_x86_64, macosx_11_0_arm64, win_amd64.

For pytest fixture support:

pip install "llmentary[pytest]"

For the quickstart using openai-python:

pip install "llmentary[pytest,openai]"

Versions

llmentary.__version__ is the Python package. llmentary.proxy_version() returns the proxy semver (for example "0.4.1"), or None when no binary resolves. proxy_version_line() is the full llmentary --version line.

Changed in 0.5.1: proxy_version() used to return that full line. Code that did proxy_version().split()[1] should call proxy_version() for the semver, or proxy_version_line() for the line.

from llmentary import __version__, proxy_version, proxy_version_line

print(__version__)
print(proxy_version())
print(proxy_version_line())

Quickstart

Point pytest at an existing proxy, or let the fixture start one:

export LLMENTARY_PROXY_URL=http://127.0.0.1:7777
export LLMENTARY_CONTROL_URL=http://127.0.0.1:7778
pytest

export LLMENTARY_BIN=/path/to/llmentary
export LLMENTARY_UPSTREAM_BASE_URL=https://api.openai.com/v1
export LLMENTARY_UPSTREAM_API_KEY="$OPENAI_API_KEY"
pytest

In-process tests that can set headers:

from openai import OpenAI


def test_tool_flow(llmentary):
    client = OpenAI(
        api_key="test-key",
        base_url=llmentary.openai_base_url,
        default_headers=llmentary.headers,
    )

    first = client.chat.completions.create(
        model="gpt-4.1-mini",
        messages=[{"role": "user", "content": "Weather in Paris?"}],
        tools=[
            {
                "type": "function",
                "function": {
                    "name": "get_weather",
                    "parameters": {
                        "type": "object",
                        "properties": {"city": {"type": "string"}},
                        "required": ["city"],
                    },
                },
            }
        ],
    )
    tool_call = first.choices[0].message.tool_calls[0]

    client.chat.completions.create(
        model="gpt-4.1-mini",
        messages=[
            {"role": "user", "content": "Weather in Paris?"},
            first.choices[0].message,
            {"role": "tool", "tool_call_id": tool_call.id, "content": '{"weather":"sunny"}'},
        ],
    )

    llmentary.expect().call_count(2).tool_called("get_weather").args_subset(
        "get_weather", {"city": "Paris"}
    ).tool_result_fed_back("get_weather").no_errors()

Black-box / import-time clients that cannot send headers: set the service base URL to llmentary.path_base_url() inside the test, then import the app. The session id exists only after the fixture runs, so a module-level import is too early.

import importlib


def test_import_time_client(llmentary, monkeypatch):
    monkeypatch.setenv("OPENAI_BASE_URL", llmentary.path_base_url())
    app = importlib.import_module("myapp")
    app.client.chat.completions.create(
        model="gpt-4.1-mini",
        messages=[{"role": "user", "content": "ping"}],
    )
    llmentary.expect().prompt_contains("ping").no_errors()

A path prefix isolates client processes, not conversations. One process with one env-configured SDK client is one session. For N parallel conversations use one of: (a) one worker process per session; (b) construct the SDK client per conversation with base_url=lm.path_base_url(); (c) headers/baggage when the app can set them; (d) run conversations sequentially with DELETE between them. A second bus worker needs its own topic or partition; two consumer groups on one topic both get every event.

Prove isolation with isolated_from. The rule is the isolation spec: same canned user question in two sessions is not a leak; a foreign user turn replayed as history is. Later calls introduce each new user-role message. An empty or unknown other session fails unless you pass allow_empty. isolated_from waits on a Session or session id with the same wait semantics as expect(), so a leak introduced by a still-running call on the other side is included; a pre-fetched trace is used as given. Comparison is exact (normalized), never substring.

other.expect().isolated_from(llmentary)
llmentary.expect().isolated_from(other)

See the proxy isolation spec (DOG-29 / DOG-32 / DOG-33), black-box guide, and assertions guide.

The function-scoped llmentary fixture returns a Session: it creates a unique session id, exposes headers with X-Test-Session, waits for proxy quiescence before assertions, and deletes the session during teardown.

Waiting for calls

wait asks the proxy to return the session trace once the session has been idle for quiet, or to fail when timeout elapses. The proxy only reads these query parameters:

Override the defaults with environment variables. Each accepts a Go duration (45s, 200ms) or a bare number of seconds (45, 0.2):

The client HTTP deadline is timeout + quiet + 5s, so the client cannot abort before the proxy answers. A timeout is an error: wait timed out after 30s on session X (k calls so far, still active: n). Raise LLMENTARY_WAIT_TIMEOUT …. When the 504 includes error.in_flight, the message also lists those still- running calls (#seq METHOD path phase). Older proxies omit that array; the client then keeps the count-only form, or omits still active when the count is unknown.

wait on a session that was never created (or was DELETEd):

from llmentary import SessionNotFound, WaitTimeoutError

try:
    llmentary.wait(timeout=3, quiet=0.2, min_calls=0)
except SessionNotFound:
    pass

try:
    llmentary.wait(timeout=3, quiet=0.2, min_calls=1)
except WaitTimeoutError:
    pass

wait() still raises SessionNotFound on that 404. expect() without allow_empty=True turns it into AssertionError('no calls recorded for session …; known sessions: …') — it does not return an empty expectation you can chain. Use expect_no_calls() or expect(allow_empty=True) for the negative test. A never-created session that will be filled by an async worker should wait with min_calls=1 (or higher), not 0.

Assertions

llmentary.expect().call_count(1).tool_called("search").called_times("search", 1)
llmentary.expect_no_calls()
llmentary.expect(allow_empty=True).call_count(0)
llmentary.query(api_type="responses", model="gpt-4.1-mini").expect().no_errors()
llmentary.query().without_tools().expect().call_count(1).request_param(
    "response_format.type", "json_schema"
)
mark = llmentary.mark()
llmentary.expect(since=mark).final_response_mentions_any("20", "sunny")

with llmentary.soft_expect() as expect:
    expect.tool_called("search")
    expect.response_contains("done")

Supported deterministic assertions include call count (call_count), tool calls (tool_called, not_called, called_times, args_subset, args_matcher, order, parallel_tool_calls, tool_result_fed_back), request and finish metadata (model, request_param, finish_reason), usage and timing (tokens, latency, ttft, retries, no_retries), errors (no_errors, has_error, mid_stream_error), prompt or response text (prompt_contains, prompt_regex, response_contains, response_regex, response_json_valid, response_json_schema), and spec observability (no_spec_violations, no_ignored_fields). Failures raise AssertionError with the session trace summary. A filter or since= that matches zero calls fails no_errors() / not_called() unless you call allow_empty() first. expect() itself still fails on a never-created session unless you pass allow_empty=True. Use llmentary.list_sessions() when a wait or expect fails with zero calls, so the message can name the known session ids (once).

Negative tests — asserting zero LLM calls:

# reading history / a GET that must not hit the model
unused.expect_no_calls(quiet=0.2)
unused.expect(allow_empty=True).call_count(0)
active.expect().allow_empty().isolated_from(unused)

Testing interruptions / barge-in: cancel a streaming call (~50 ms after send, or after the first chunk) and read the typed abort fields:

stream.close()
expectation = llmentary.expect().aborted()
call = next(call for call in expectation.trace.calls if call.client_aborted)
assert call.client_aborted
assert call.upstream_called is True
assert call.abort_phase in (None, "before_headers", "after_headers")
assert call.finish_reason in {"cancelled", "unknown"}
assert call.http_status != 502
assert "status=aborted" in expectation.trace.trace_summary()

client_aborted prefers the top-level Call field and falls back to normalized.client_aborted on older proxies. abort_phase is before_headers or after_headers when the call was aborted, and omitted (None) otherwise. upstream_called is the top-level Call field (True/False), or None on older proxies. Closing after [DONE] or a terminal Responses event is not an abort. Proxy 0.3.0 still records finish_reason=unknown on abort; cancelled is the documented value.

Trace-summary status= is ok, error, or aborted. Both abort phases print status=aborted (a scan for status=error must not miss an after-headers cancel that already has http=200). http= is included only when an upstream status was recorded (after-headers, typically 200; omitted for before-headers). stream_truncated is printed only when the proxy recorded a truncated stream (after-headers). phase= is printed when abort_phase is known.

Call id values (call_3) are unique within one proxy process and can interleave across sessions. CapturedCall.seq is 1-based per session (sequence_number() is an alias). The trace summary prints #seq (id).

See docs/api.md, docs/pytest.md, and the proxy assertions guide.

llmentary repositories

License

Licensed under MIT, see LICENSE