@wdio/logger

What is @wdio/logger?

The @wdio/logger package is a utility used within the WebdriverIO testing framework to facilitate logging. It allows developers to create namespaced loggers that can be used to output messages to the console or to files, depending on the configuration. It is designed to work seamlessly with the WebdriverIO ecosystem but can also be used independently for logging purposes in Node.js applications.

What are @wdio/logger's main functionalities?

Creating a Logger Instance

This feature allows you to create a new logger instance with a specific namespace. You can then use this instance to log messages at different levels, such as info, warn, error, etc.

const logger = require('@wdio/logger').default('my-logger');
logger.info('This is an info message.');

Setting Log Levels

This feature allows you to set the log level for a specific logger instance. Messages below the set level will not be logged.

const logger = require('@wdio/logger').default('my-logger');
logger.setLevel('info');
logger.info('This will be logged.');
logger.debug('This will not be logged.');

Logging Messages

This feature is used to log messages at different severity levels. The available methods are info, warn, error, and others, each corresponding to a level of importance.

const logger = require('@wdio/logger').default('my-logger');
logger.info('Informational message');
logger.warn('Warning message');
logger.error('Error message');

Other packages similar to @wdio/logger

winston

Winston is a multi-transport async logging library for Node.js. It is one of the most popular logging libraries and offers more flexibility and configuration options compared to @wdio/logger. It supports multiple storage options for logs, such as files, databases, and remote services.

pino

Pino is a very low overhead Node.js logger, which focuses on performance. It provides a different set of trade-offs compared to @wdio/logger, emphasizing speed and efficiency over configurability and integration with specific frameworks like WebdriverIO.

bunyan

Bunyan is a simple and fast JSON logging library for Node.js services. It has similar functionalities to @wdio/logger but also includes features like log rotation and streams, which can be more suitable for complex logging needs.

README

WDIO Logger Utility

A helper utility for logging of WebdriverIO packages

This package is used across all WebdriverIO packages to log information using the loglevel package. It can also be used for any other arbitrary Node.js project.

Install

To install the package just call

npm install @wdio/logger

or when adding it to a WebdriverIO subpackage:

lerna add @wdio/logger --scope <subpackage>

Usage

The package exposes a logger function that you can use to register an instance for your scoped package:

import logger from '@wdio/logger'

const log = logger('myPackage')
log.info('some logs')

For more info see loglevel package on NPM.

Custom Log Levels

This package extends the log levels available in loglevel by introducing a new level called progress.

The progress level is particularly useful when you need to dynamically update a specific line in the terminal. For example, it can be utilized to display the download progress of browsers or drivers.

Notably, the progress level is equivalent to the info level. Therefore, if you set the log level to error or silent, any progress logs will be suppressed.

It's important to mention that progress writes directly to process.stdout, and these logs won't be captured in any log files.

To ensure consistent formatting with subsequent logs while using progress, it's essential to clear it at the end. To do so, simply call progress with an empty string, which will clear the last line:

log.progress('')

Illustrative Usage of Progress

import logger from '@wdio/logger';

const log = logger('internal');

const totalSize = 100;
let uploadedSize = 0;

const uploadInterval = setInterval(() => {
	const chunkSize = 10;
	uploadedSize += chunkSize;
	const data = `Progress: ${(uploadedSize * 100) / totalSize}%`;
	log.progress(data);
	if (uploadedSize >= totalSize) {
		clearInterval(uploadInterval);
		log.progress(''); // Called at the end to maintain the alignment of subsequent logs.
		console.log('Upload complete.');
	}
}, 100);