A debug logger with a logtron interface.

This logger is designed for tests; it prints info & above and prints debugs if you set NODE_DEBUG=mylibrary

var DebugLogtron = require("debug-logtron");

var logger = DebugLogtron('mylibrary');

logger.debug('some fixed string', { some: 'meta object' });
logger.info('some fixed string', { some: 'meta object' });
logger.warn('some fixed string', { some: 'meta object' });
logger.error('some fixed string', { some: 'meta object' });

It writes all logs to stderr. If you call logger.error() or logger.fatal() it will throw exceptions. any error callsites are bugs.

warns go to stderr by default.

You can use the .whitelist() and .items() method to make testing easier

var DebugLogtron = require('debug-logtron');
var test = require('tape');

test('some module', function t(assert) {
    var logger = NullLogtron('mything');
    var thing = new Thing({ logger: logger })

    logger.whitelist('error', 'some msg');

    thing.doStuff();

    var items = logger.items();
    assert.equal(items.filter(function (x) {
        return x.levelName === 'error'
    }).length, 1, 'thing writes to logger.error()');
    assert.end();
});

Whilst it is recommended that you minimize state between tests by creating a new instance of debug-logtron, it is possible to remove a whitelisted item by calling .unwhitelist with the same arguments.

This library will re throw any .error() or .fatal() callsites.

Any warns and infos got to stderr.

Any debugs / access can be made visible using NODE_DEBUG=mylibrary.

You can turn colors off with --color false

If you want to see trace() logs you must set NODE_DEBUG=mylibrary TRACE=1

Warning: This a logger for testing! Not a default logger.

If you want to add a default logger to your dependencies then I strongly recommend you use null-logtron

You want to instrument your application and your libraries with a production application logger. A logger that writes somewhere in production.

However for your writing tests for both your libraries and your applications you probably do not want to see all of your logs spewing on STDOUT by default.

This is where debug-logtron comes in, You can start your app or libraries with the debug logger in your tests which allows the test runner to decide when to spew.

This works great together with itape --trace where you can use itape to turn on and off trace mode.

// TODO. State what the module does.

npm install debug-logtron

npm test

• Raynos