Respect messageKey option when mergeHapiLogData is set (#138)

index.js

@@ -76,6 +76,7 @@ async function register (server, options) {
   }
 
   const mergeHapiLogData = options.mergeHapiLogData
+  const messageKey = options.messageKey || 'msg'
   const getChildBindings = options.getChildBindings ? options.getChildBindings : (request) => ({ req: request })
   const shouldLogRequestStart = typeof options.logRequestStart === 'function'
     ? (request) => options.logRequestStart(request)
@@ -244,7 +245,7 @@ async function register (server, options) {
     var logObject
     if (mergeHapiLogData) {
       if (typeof data === 'string') {
-        data = { msg: data }
+        data = { [messageKey]: data }
       }
 
       logObject = Object.assign({ tags }, data)

test.js

@@ -1275,6 +1275,31 @@ experiment('logging with mergeHapiLogData option enabled', () => {
     server.log(['info'], 'hello world')
     await finish
   })
+
+  test('respects `messageKey` option', async () => {
+    const server = getServer()
+    let done
+    const finish = new Promise(function (resolve, reject) {
+      done = resolve
+    })
+    const stream = sink(data => {
+      expect(data).to.include({ message: 'hello world' })
+      done()
+    })
+    const plugin = {
+      plugin: Pino,
+      options: {
+        stream: stream,
+        level: 'info',
+        mergeHapiLogData: true,
+        messageKey: 'message'
+      }
+    }
+
+    await server.register(plugin)
+    server.log(['info'], 'hello world')
+    await finish
+  })
 })
 
 experiment('custom serializers', () => {