Merge pull request #2 from trivialsoftware/null-logging

Added null logger

Author: Morgul

Readme.md

@@ -59,9 +59,10 @@ const basicLogger = logging.getLogger('basic');
 const overriddenLogger = logging.getLogger('overridden', { streams: [ /* ... */ ] });
 ```
 
-#### Usage with Unit Tests
+### Usage with Unit Tests
 
-Generally, when you're running unit tests, you don't want most logging. The easiest way to achieve this is by setting the `LOG_LEVEL` environment variable to `'ERROR'`. You can do this at the top of your unit test:
+Generally, when you're running unit tests, you don't want most logging. The easiest way to achieve this is by setting
+the `LOG_LEVEL` environment variable to `'ERROR'`. You can do this at the top of your unit test:
 
 ```javascript
 // Set `LOG_LEVEL` before importing your code that imports `trivial-logging`
@@ -74,6 +75,37 @@ const { expect } = require('chai');
 
 Make sure that you set `process.env.LOG_LEVEL` _before_ importing any code that imports `trivial-logging`.
 
+### Null Logger (Disabling all logging)
+
+Trivial Logging has a `NullLogger` implementation. This turns all logging operations into a noop. This means that there
+will be no output, and very little overhead from logging calls. This is helpful with debugging, or for unit tests.
+
+This can be enabled by setting `LOG_NULL` to any value. For example:
+
+```bash
+$ env LOG_NULL="true" node ./example.js
+```
+
+This can also be enabled via the config file, with the `nullLogger` property being set to true:
+
+```javascript
+const logging = require('trivial-logging');
+
+const config = {
+    nullLogger: true
+};
+
+// This stores the configuration
+logging.init(config);
+
+// This gets a null logger
+const logger = logging.getLogger('some logger');
+
+// All calls to this logger are noops
+logger.info("Some logging.");
+logger.fatal("Some other logging.");
+```
+
 ## API
 
 ### `init(config)`

example/null-logging-example.js

@@ -0,0 +1,32 @@
+//----------------------------------------------------------------------------------------------------------------------
+// logging-example.js - Brief description for logging-example.js module.
+//
+// @module
+//----------------------------------------------------------------------------------------------------------------------
+
+const logging  = require('../logging');
+
+//----------------------------------------------------------------------------------------------------------------------
+
+logging.init({ debug: true, nullLogger: true });
+logging.setRootLogger('example');
+
+//----------------------------------------------------------------------------------------------------------------------
+
+const logger = logging.loggerFor(module);
+
+logger.trace('more tracing!');
+logger.debug('testing?');
+logger.info('This is a test.', logger.dump({ msg: 'with an object' }), logger.dump({ other: { nested: { object: { of: { doom: true, foo: 23, bar: 'apples', baz: null } } } }}));
+logger.warn('This is a warning. No object this time.');
+logger.error('This is an error.', new Error('TESTING!!!!! And stuff.'));
+
+const logger2 = logging.getLogger('other logger');
+
+logger2.trace('more tracing!');
+logger2.debug('testing?');
+logger2.info('This is a test.', logger.dump({ msg: 'with an object' }));
+logger2.warn('This is a warning. No object this time.');
+logger2.error('This is an error.', new Error('TESTING!!!!! And stuff.'));
+
+//----------------------------------------------------------------------------------------------------------------------

lib/nullLogger.js

@@ -0,0 +1,40 @@
+//----------------------------------------------------------------------------------------------------------------------
+// nullLogger.js - Brief description for nullLogger.js module.
+//
+// @module
+//----------------------------------------------------------------------------------------------------------------------
+
+const { EventEmitter } = require('events');
+
+//----------------------------------------------------------------------------------------------------------------------
+
+class NullLogger extends EventEmitter
+{
+    // Bunyan Properties
+    get stdSerializers(){ return {}; }
+
+    // Bunyan API
+    child(){ return new NullLogger(); }
+    level(){ return 'INFO'; }
+    levels(){ return ['INFO']; }
+    addSerializers(){}
+    addStream(){}
+    reopenFileStreams(){}
+    close(){}
+
+    // Logging API
+    trace(){}
+    debug(){}
+    info(){}
+    warn(){}
+    error(){}
+    fatal(){}
+} // end NullLogger
+
+//----------------------------------------------------------------------------------------------------------------------
+
+module.exports = {
+    createLogger(){ return new NullLogger(); }
+}; // end exports
+
+//----------------------------------------------------------------------------------------------------------------------

logging.js

@@ -8,10 +8,11 @@ const { inspect } = require('util');
 const path = require('path');
 
 const _ = require('lodash');
-const logging = require('bunyan');
 const bunyanDebugStream = require('bunyan-debug-stream');
 const colors = require('colors');
 
+let logging = require('bunyan');
+
 //----------------------------------------------------------------------------------------------------------------------
 
 class LoggingService {
@@ -27,6 +28,11 @@ class LoggingService {
             this.mainDir = process.cwd();
         } // end try
 
+        if(process.env.LOG_NULL)
+        {
+            logging = require('./lib/nullLogger');
+        } // end if
+
         // Setup default streams
         this.streams = [
             {
@@ -51,6 +57,11 @@ class LoggingService {
         // Pull out the streams config, with sane defaults.
         const streams = ((config.logging || config).streams) || this.streams;
 
+        if(config.nullLogger)
+        {
+            logging = require('./lib/nullLogger');
+        } // end if
+
         this.streams = _.map(streams, (stream) =>
         {
             // We only _ever_ override the process.stdout steam.