pino-test

library2.0.0jsnpmunverified

pino-test is a utility library designed to simplify the process of testing applications that use the Pino logger. It provides a `sink()` method to create a transform stream that captures Pino's JSON log output, allowing for easy inspection and assertion within test suites. The library also offers `once()` and `consecutive()` helpers to assert single or multiple log entries against expected values, optionally with custom assertion functions. The current stable version is 2.0.0, which includes code modernization and drops support for older Node.js versions. While its release cadence isn't strictly fixed, major versions appear to be released as significant updates or breaking changes warrant, with v2.0.0 following v1.0.0 after some time. It differentiates itself by tightly integrating with Pino's stream-based logging for efficient and precise log verification without complex mock setups.

testing observability

npm install pino-test

github ↗package ↗

INSTALL

IMPORT

SIG · PINO-TEST

pino-test

testingjavascriptv2.0.0

Install

—

Import

—

Disk

—

Pass rate

0/ 6

Env Coverage0 / 6

glibc

18–22

musl

18–22

Install & Compatibility

Where this runs

tested against v? · npm install

Install × environment matrix

Each cell = how many times install + import succeeded across repeated harness runs. Partial = flaky.
glibc = Debian/Ubuntu slim · musl = Alpine Linux

musl

node 18–226 runs

build_error

glibc

node 18–226 runs

build_error

Code

Verified usage

Verified import paths — ran on the pinned version, not inferred.

pinoTest

✓ const pinoTest = require('pino-test');

✗ import pinoTest from 'pino-test';

For CommonJS, the module exports an object containing all utilities. For ESM, use `import * as pinoTest from 'pino-test'` or named imports for specific functions.

sink

✓ import { sink } from 'pino-test';

✗ const sink = require('pino-test').sink;

This is the recommended way to import individual functions in ESM. In CommonJS, access `sink` as a property of the main `pinoTest` object.

once

✓ import { once } from 'pino-test';

Used to assert a single log entry. Access as `pinoTest.once` in CommonJS environments.

Demonstrates how to create a `pino-test` sink, configure a Pino logger to use it, and assert single log messages using `pinoTest.once`, including an example with a custom assertion function.

import test from 'node:test'; import pino from 'pino'; import { sink, once } from 'pino-test'; test('pino should log an info message', async () => { const pinoSink = sink(); const logger = pino(pinoSink); logger.info('hello world'); const expected = { msg: 'hello world', level: 30 }; await once(pinoSink, expected); }); // Example with a custom assertion function function customAssert (received, expected, msg) { if (received.msg !== expected.msg) { throw new Error(`Expected msg '${expected.msg}' but received '${received.msg}'`); } } test('pino should log an info message using a custom assert function', async () => { const pinoSink = sink(); const logger = pino(pinoSink); logger.info('hello world from custom'); const expected = { msg: 'hello world from custom', level: 30 }; await once(pinoSink, expected, customAssert); });

Debug

Known issues

breakingVersion 2.0.0 drops support for older Node.js versions. Applications running on Node.js versions prior to the minimum supported by v2.0.0 (typically Node.js 16 or higher for modern Pino ecosystem libraries) will fail.

fix

Upgrade your Node.js environment to a supported LTS version (e.g., Node.js 16, 18, or 20).

affects: >=2.0.0

gotchaThe `once()` and `consecutive()` assertion helpers include default assertions for `time`, `pid`, and `hostname`. These fields are automatically added by Pino and can cause unexpected assertion failures if not explicitly accounted for or overwritten in your expected log object.

fix

Ensure your `expected` object in `once()` or `consecutive()` includes realistic values for `time`, `pid`, and `hostname` if you intend to assert them, or provide a custom `is` function to ignore these fields for comparison.

affects: >=1.0.0

gotchaPino log streams expect valid JSON objects (JSON Lines). Writing malformed or non-JSON data directly to a `pinoTest.sink()` stream will result in parsing errors and potentially stream destruction, depending on configuration.

fix

Always ensure data written to `pinoTest.sink()` is valid JSON. For robustness, configure `sink({ destroyOnError: false, emitErrorEvent: true })` to handle parsing errors gracefully via an 'error' event without terminating the stream.

affects: >=1.0.0

Errors

Common errors & fixes

Unexpected token h in JSON at position 0

Non-JSON data was written directly to the `pinoTest.sink()` stream, which expects JSON Lines input.

fix

Ensure all data sent to the `pinoTest.sink()` stream is a valid JSON string, as Pino's default output format is JSON Lines.

AssertionError: Input A is different from Input B

The expected log object provided to `pinoTest.once()` or `pinoTest.consecutive()` does not exactly match the received log, potentially due to automatically added fields like `time`, `pid`, or `hostname`.

fix

Adjust your `expected` object to accurately reflect the full log structure, including auto-generated fields, or pass a custom `is` function to `once` or `consecutive` to define specific comparison logic for only the fields you care about.

Cannot find module 'pino'

`pino` is a peer dependency of `pino-test` and was not installed in the project's `node_modules`.

fix

Install `pino` explicitly: `npm install pino` or `npm install pino --save-dev`.

Upgrade

Version history

2.0.0latest on npm

Audit

Dependencies

pinorequiredPeer dependency. `pino-test` is designed to work with Pino logger streams, so Pino itself is required for any practical use.

Agent activity

14 hits · last 30 days

node

OpenAI (training)

Resources

githubhttps://github.com/pinojs/pino-test ↗

packagehttps://www.npmjs.com/package/pino-test ↗