fix: don't use error message as log message for object-only patterns STONK-487 (#4)

Author: madyanmalfi

src/index.ts

@@ -108,10 +108,7 @@ export const structuredLogger = (opts: StructuredLoggerOptions = {}) => ({
       return
     }
 
-    const { messageTemplate, structured, error } = extractStructuredData(
-      args,
-      getErrorKey(this),
-    )
+    const { messageTemplate, structured, error } = extractStructuredData(args)
     const structuredWithBindings = { ...this.bindings(), ...structured }
     const formattedMessage = reformatMessageWithRemainingArgs(
       formatMessage(messageTemplate, structuredWithBindings),
@@ -149,7 +146,6 @@ const formatMessage = (
 
 const extractStructuredData = (
   args: Parameters<LogFn>,
-  errorKey: string,
 ): {
   messageTemplate: string
   structured: Record<string, unknown>
@@ -185,13 +181,10 @@ const extractStructuredData = (
   if (typeof args[0] === 'object' && args[0] !== null) {
     const obj = args.shift() as Error | Record<string, unknown>
     if (obj instanceof Error) {
-      return { messageTemplate: obj.message || '', structured: {}, error: obj }
+      return { messageTemplate: '', structured: {}, error: obj }
     }
     const structured = obj
-    const errValue = structured[errorKey]
-    const messageTemplate =
-      errValue instanceof Error ? errValue.message || '' : ''
-    return { messageTemplate, structured }
+    return { messageTemplate: '', structured }
   }
 
   // this should never happen

test/index.spec.ts

@@ -427,13 +427,13 @@ describe('structured logger', () => {
   })
 
   describe('object without message', () => {
-    it('uses error message when only an Error is passed', () => {
+    it('does not use error message as log message when only an Error is passed', () => {
       const error = new Error('Something went wrong')
       logger.error(error)
 
       expect(capturedLogs).toHaveLength(1)
-      expect(capturedLogs[0].msg).toBe('Something went wrong')
-      expect(capturedLogs[0].msg_tpl).toBe('Something went wrong')
+      expect(capturedLogs[0].msg).toBe('')
+      expect(capturedLogs[0].msg_tpl).toBe('')
       expect(capturedLogs[0].err).toEqual({
         message: 'Something went wrong',
         type: 'Error',
@@ -442,13 +442,13 @@ describe('structured logger', () => {
       expect(capturedLogs[0].data).toBeUndefined()
     })
 
-    it('uses err.message when object with error is passed', () => {
+    it('does not use err.message as log message when object with error is passed', () => {
       const error = new Error('Internal server error')
       logger.error({ err: error })
 
       expect(capturedLogs).toHaveLength(1)
-      expect(capturedLogs[0].msg).toBe('Internal server error')
-      expect(capturedLogs[0].msg_tpl).toBe('Internal server error')
+      expect(capturedLogs[0].msg).toBe('')
+      expect(capturedLogs[0].msg_tpl).toBe('')
       expect(capturedLogs[0].err).toEqual({
         message: 'Internal server error',
         type: 'Error',
@@ -462,7 +462,7 @@ describe('structured logger', () => {
       logger.error({ err: error, ctx: 'ExceptionFilter', status_code: 500 })
 
       expect(capturedLogs).toHaveLength(1)
-      expect(capturedLogs[0].msg).toBe('Unhandled exception')
+      expect(capturedLogs[0].msg).toBe('')
       expect(capturedLogs[0].err).toEqual({
         message: 'Unhandled exception',
         type: 'Error',
@@ -500,7 +500,7 @@ describe('structured logger', () => {
       customLogger.error({ pinoError: error, ctx: 'Test' })
 
       expect(capturedLogs).toHaveLength(1)
-      expect(capturedLogs[0].msg).toBe('Custom key error')
+      expect(capturedLogs[0].msg).toBe('')
       expect(capturedLogs[0].pinoError).toEqual({
         message: 'Custom key error',
         type: 'Error',
@@ -533,7 +533,7 @@ describe('structured logger', () => {
       logger.error({ err: exception, ctx: 'ExceptionsHandler' })
 
       expect(capturedLogs).toHaveLength(1)
-      expect(capturedLogs[0].msg).toBe('Internal Server Error')
+      expect(capturedLogs[0].msg).toBe('')
       expect(capturedLogs[0].err).toEqual(
         expect.objectContaining({
           message: 'Internal Server Error',
@@ -573,9 +573,7 @@ describe('structured logger', () => {
       logger.error({ err: exception, ctx: 'DatabaseModule' })
 
       expect(capturedLogs).toHaveLength(1)
-      expect(capturedLogs[0].msg).toBe(
-        '{"statusCode":503,"message":"Database connection failed","error":"Service Unavailable"}',
-      )
+      expect(capturedLogs[0].msg).toBe('')
       expect(capturedLogs[0].err).toEqual(
         expect.objectContaining({
           message:
@@ -590,7 +588,7 @@ describe('structured logger', () => {
       logger.child({ request_id: 'abc-123' }).error({ err: new Error('fail') })
 
       expect(capturedLogs).toHaveLength(1)
-      expect(capturedLogs[0].msg).toBe('fail')
+      expect(capturedLogs[0].msg).toBe('')
       expect(capturedLogs[0].err).toEqual({
         message: 'fail',
         type: 'Error',