Added log level functions and unit test

src/index.js

@@ -7,4 +7,19 @@ const tracer = Object.assign(new GlobalTracer(), opentracing)
 tracer.express = express
 tracer.request = request
 
+function logFn (level) {
+  return function log (ctx, event, data) {
+    if (level === 'debug') {
+      data = Object.assign({ debug: true }, data)
+    } else if (level === 'error') {
+      data = Object.assign({ error: true }, data)
+    }
+    ctx.span.log(Object.assign({ event: event , level: level}, data))
+  }
+}
+tracer.debug = logFn('debug')
+tracer.info = logFn('info')
+tracer.warn = logFn('warn')
+tracer.error = logFn('error')
+
 export default tracer

test/tracer.spec.js

@@ -1,7 +1,7 @@
 'use strict'
 
 const should = require('should')
-
+const _ = require('lodash')
 const tracer = require('../src')
 const Stream = require('./util/stream.js')
 
@@ -119,6 +119,35 @@ describe('tracer', () => {
         }
       })
     })
+
+    it('should log events by level', () => {
+      let ctx = { span: tracer.startSpan('originating', () => {}) }
+
+      tracer.debug(ctx, 'DebugEvent', { foo: 'bar' })
+      tracer.info(ctx, 'InfoEvent', { foo: 'bar' })
+      tracer.warn(ctx, 'WarnEvent', { foo: 'bar' })
+      tracer.error(ctx, 'ErrorEvent', { foo: 'bar' })
+
+      let logs = ctx.span._fields.logs
+      let debugEvent = _.omit(_.find(logs, (log) => {
+        return log.level === 'debug'
+      }), ['timestamp'])
+      let infoEvent = _.omit(_.find(logs, (log) => {
+        return log.level=== 'info'
+      }), ['timestamp'])
+      let warnEvent = _.omit(_.find(logs, (log) => {
+        return log.level === 'warn'
+      }), ['timestamp'])
+      let errorEvent = _.omit(_.find(logs, (log) => {
+        return log.level === 'error'
+      }), ['timestamp'])
+
+      debugEvent.should.eql({ foo: 'bar', event: 'DebugEvent', level: 'debug', debug: true })
+      infoEvent.should.eql({ foo: 'bar', event: 'InfoEvent', level: 'info' })
+      warnEvent.should.eql({ foo: 'bar', event: 'WarnEvent', level: 'warn' })
+      errorEvent.should.eql({ foo: 'bar', event: 'ErrorEvent', level: 'error', error: true })
+
+    })
   })
 
   describe('with custom propagators', () => {