---
id: pytest-structlog
version: "1.2"
license: MIT
license_treatment: permissive
maintenance: active
---

# pytest-structlog — Structured logging assertions

License: permissive · Maintenance: active · Downloads: 286.5K/mo

## What it is and what it does

pytest-structlog is a pytest plugin that integrates with structlog to capture and inspect structured log events during testing. It provides a `log` fixture that exposes captured events as a list and offers helper methods like `log.has()` for asserting that specific log messages with particular context were emitted. The fixture automatically configures structlog for testing purposes, stripping away production processors and replacing them with a test-friendly list-based collector.

The package lets you verify not just that logging occurred, but exactly what was logged—including event messages, log levels, and arbitrary context fields. You can assert on individual events, compare sequences of events, count occurrences, and use flexible matching patterns. It also provides command-line options and configuration file support to customize which structlog processors are kept or removed during testing, allowing you to preserve custom processors when needed.

Use it for:

- Verify that your application logs the correct messages and context when specific code paths execute.
- Assert that errors or warnings are logged with the expected fields and severity levels during exception handling.
- Test that batch operations log the right number of events and include required tracking or debugging information.
- Validate that custom structlog processors are invoked correctly by inspecting the final event dictionaries.
- Ensure sensitive information is not accidentally logged by checking event contents in security-focused tests.

## Worth the install?

AI-flagged interpretation of the facts above — verify before relying.

Provides a pytest fixture for capturing and asserting on structured logs produced by structlog, enabling test-friendly inspection of log events and their context.

Yes. Low install friction, active maintenance, no known vulnerabilities, and MIT licensing make it a safe choice. If your test suite uses structlog for structured logging, this fixture is the standard way to assert on log output in pytest—it directly addresses a gap in testing structured logs that would otherwise require manual mocking or post-test log file inspection.

## Install

pip install pytest-structlog
uv add pytest-structlog
poetry add pytest-structlog

## Installing pytest-structlog

Before you install: Low friction: pure Python wheel with only pytest and structlog as runtime dependencies. Actively maintained with a recent release (338 days ago) and an active repository.

License in practice: MIT license permits use in proprietary and open-source projects with minimal restrictions; attribution required.

Quickstart:

pip install pytest-structlog

# In your test file:
from pytest_structlog import StructuredLogCapture

def test_logging(log: StructuredLogCapture):
    # Your code that logs via structlog
    assert log.has("event message")
    assert len(log.events) == 1

Requires Python 3.8 or later; structlog must be configured in the code under test.

Verify before relying:

- Whether the fixture automatically captures all structlog output or requires explicit configuration in code under test.
- Performance impact when capturing large numbers of log events in a single test.

## Package facts

- License: MIT (permissive)
- Python support: supports_current
- Install friction: low
- Maintenance: active
- Downloads: 286.5K/month (top 15,000 on PyPI)
- Known vulnerabilities: none known

## Tags

pytest structlog fixture, structured logging test assertions, capture structlog events in tests, pytest log verification, structlog test helper, assert on structured logs, pytest logging fixture, pytest-plugin, structured-logging, test-assertions

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