Improve error logging during ChannelConnection._handleFatalError (#812)

Author: bigmontz

packages/bolt-connection/src/connection/connection-channel.js

@@ -277,7 +277,7 @@ export default class ChannelConnection extends Connection {
 
     if (this._log.isErrorEnabled()) {
       this._log.error(
-        `experienced a fatal error ${json.stringify(this._error)}`
+        `experienced a fatal error caused by ${this._error} (${json.stringify(this._error)})`
       )
     }
 

packages/bolt-connection/test/connection/connection-channel.test.js

@@ -129,6 +129,7 @@ describe('ChannelConnection', () => {
   describe('._handleFatalError()', () => {
     describe('when there is not current failure on going', () => {
       const thrownError = newError('some error', 'C')
+      let loggerFunction;
       let notifyFatalError;
       let connection;
 
@@ -138,9 +139,10 @@ describe('ChannelConnection', () => {
           notifyFatalError,
           currentFailure: null
         }
-        
+        loggerFunction = jest.fn()
+        const logger = new Logger('info', loggerFunction)
         const protocolSupplier = () => protocol
-        connection = spyOnConnectionChannel({ protocolSupplier })
+        connection = spyOnConnectionChannel({ protocolSupplier, logger })
       })
 
       it('should set connection state to broken', () => {
@@ -160,11 +162,22 @@ describe('ChannelConnection', () => {
 
         expect(notifyFatalError).toHaveBeenCalledWith(thrownError)
       })
+
+      it('should log the thrownError', () => {
+        connection._handleFatalError(thrownError)
+
+        expect(loggerFunction).toHaveBeenCalledWith(
+          'error',
+          `${connection} experienced a fatal error caused by Neo4jError: some error ` +
+            '({"code":"C","name":"Neo4jError"})'
+        )
+      })
     })
 
     describe('when there is current failure on going', () => {
       const thrownError = newError('some error', 'C')
       const currentFailure = newError('current failure', 'ongoing')
+      let loggerFunction;
       let notifyFatalError;
       let connection;
 
@@ -174,9 +187,10 @@ describe('ChannelConnection', () => {
           notifyFatalError,
           currentFailure
         }
-        
+        loggerFunction = jest.fn()
+        const logger = new Logger('info', loggerFunction)
         const protocolSupplier = () => protocol
-        connection = spyOnConnectionChannel({ protocolSupplier })
+        connection = spyOnConnectionChannel({ protocolSupplier, logger })
       })
 
       it('should set connection state to broken', () => {
@@ -196,6 +210,16 @@ describe('ChannelConnection', () => {
 
         expect(notifyFatalError).toHaveBeenCalledWith(currentFailure)
       })
+
+      it('should log the currentFailure', () => {
+        connection._handleFatalError(thrownError)
+
+        expect(loggerFunction).toHaveBeenCalledWith(
+          'error',
+          `${connection} experienced a fatal error caused by Neo4jError: current failure ` +
+            '({"code":"ongoing","name":"Neo4jError"})'
+        )
+      })
     })
   })