service-template-node/test/utils/logStream.js

A blueprint for MediaWiki REST API services

/* eslint-disable no-console */

'use strict';

const bunyan = require('bunyan');

function logStream(logStdout) {

    const log = [];
    const parrot = bunyan.createLogger({
        name: 'test-logger',
        level: 'warn'
    });

    function write(chunk, encoding, callback) {
        try {
            const entry = JSON.parse(chunk);
            const levelMatch = /^(\w+)/.exec(entry.levelPath);
            if (logStdout && levelMatch) {
                const level = levelMatch[1];
                if (parrot[level]) {
                    parrot[level](entry);
                }
            }
        } catch (e) {
            console.error('something went wrong trying to parrot a log entry', e, chunk);
        }

        log.push(chunk);
    }

    // to implement the stream writer interface
    function end(chunk, encoding, callback) {
    }

    function get() {
        return log;
    }

    function slice() {

        const begin = log.length;
        let end   = null;

        function halt() {
            if (end === null) {
                end = log.length;
            }
        }

        function get() {
            return log.slice(begin, end);
        }

        /* Disable eslint object-shorthand until Node 4 support is dropped */
        /* eslint-disable object-shorthand */
        return {
            halt: halt,
            get: get
        };

    }

    return {
        write: write,
        end: end,
        slice: slice,
        get: get
    };
}

module.exports = logStream;