From 22ac48396a7ef87c832bad6c6016a60ce464a03a Mon Sep 17 00:00:00 2001
From: Ryan Day <soldair@gmail.com>
Date: Wed, 26 Sep 2018 13:32:59 -0700
Subject: [PATCH 1/3] fix: assign log levels to un bound functions

binding custom log level functions to `this` with arrow functions causes unintentional behavior.
the expectation is that they should be callable the same way as logger.log

if you extend a logger instance `logger.log` will be called on `logger` whereas `logger.warn` will be called on `logger.prototype`

this fixes #1482 but I believe it should be treated as a bug. I doubt blocking extension of only part of the surface area of the instance was intended.

this sets the base for efficient child loggers that only extend write to add attributes.
---
 lib/winston/create-logger.js | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/lib/winston/create-logger.js b/lib/winston/create-logger.js
index c17780640..e426a60eb 100644
--- a/lib/winston/create-logger.js
+++ b/lib/winston/create-logger.js
@@ -45,7 +45,8 @@ class DerivedLogger extends Logger {
 
       // Define prototype methods for each log level
       // e.g. logger.log('info', msg) <––> logger.info(msg) & logger.isInfoEnabled()
-      this[level] = (...args) => {
+      // this is not an arrow function so it'll always be called on the instance not at a fixed place in the prototype chain.
+      this[level] = function(...args){
         // Optimize the hot-path which is the single object.
         if (args.length === 1) {
           const [msg] = args;

From 4f3608211b16e8e32a5765c85e9fa4d8f7b282b9 Mon Sep 17 00:00:00 2001
From: Ryan Day <ryaneday@google.com>
Date: Wed, 26 Sep 2018 14:09:12 -0700
Subject: [PATCH 2/3] test: test for custom method prototype binding

---
 lib/winston/create-logger.js |  4 ++--
 test/logger.test.js          | 27 +++++++++++++++++++++++++++
 2 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/lib/winston/create-logger.js b/lib/winston/create-logger.js
index e426a60eb..fedfadaa4 100644
--- a/lib/winston/create-logger.js
+++ b/lib/winston/create-logger.js
@@ -45,8 +45,8 @@ class DerivedLogger extends Logger {
 
       // Define prototype methods for each log level
       // e.g. logger.log('info', msg) <––> logger.info(msg) & logger.isInfoEnabled()
-      // this is not an arrow function so it'll always be called on the instance not at a fixed place in the prototype chain.
-      this[level] = function(...args){
+      // this is not an arrow function so it'll always be called on the instance instead of a fixed place in the prototype chain.
+      this[level] = function (...args) {
         // Optimize the hot-path which is the single object.
         if (args.length === 1) {
           const [msg] = args;
diff --git a/test/logger.test.js b/test/logger.test.js
index 48fa31bb4..dbc3b2063 100755
--- a/test/logger.test.js
+++ b/test/logger.test.js
@@ -66,6 +66,33 @@ describe('Logger', function () {
     })
   });
 
+  it('new Logger({ levels }) custom methods are not bound to instance', function () {
+
+    var logger = winston.createLogger({
+      level: 'error',
+      exitOnError: false,
+      transports: []
+    });
+
+    let logs = []
+
+    let extendedLogger = Object.create(logger,{
+      write:{
+        value:function(...args){
+          logs.push(args)
+        }
+      }
+    })
+
+    extendedLogger.log({test:1})
+    extendedLogger.warn({test:2})
+
+    assume(logs[0]||[]).is.eql([{test:1}])
+    assume(logs[1]||[]).is.eql([{message:{test:2},level:'warn'}])
+
+
+  });
+
   it('.add({ invalid Transport })', function () {
     var logger = winston.createLogger();
     assume(function () {

From 907a885c3b3b1b3c425fd8262b2abf08a10acebb Mon Sep 17 00:00:00 2001
From: DABH <DABH@users.noreply.github.com>
Date: Wed, 26 Sep 2018 14:52:18 -0700
Subject: [PATCH 3/3] style

---
 test/logger.test.js | 17 +++++++----------
 1 file changed, 7 insertions(+), 10 deletions(-)

diff --git a/test/logger.test.js b/test/logger.test.js
index dbc3b2063..da0beca28 100755
--- a/test/logger.test.js
+++ b/test/logger.test.js
@@ -67,30 +67,27 @@ describe('Logger', function () {
   });
 
   it('new Logger({ levels }) custom methods are not bound to instance', function () {
-
     var logger = winston.createLogger({
       level: 'error',
       exitOnError: false,
       transports: []
     });
 
-    let logs = []
+    let logs = [];
 
     let extendedLogger = Object.create(logger,{
       write:{
         value:function(...args){
-          logs.push(args)
+          logs.push(args);
         }
       }
-    })
-
-    extendedLogger.log({test:1})
-    extendedLogger.warn({test:2})
-
-    assume(logs[0]||[]).is.eql([{test:1}])
-    assume(logs[1]||[]).is.eql([{message:{test:2},level:'warn'}])
+    });
 
+    extendedLogger.log({test:1});
+    extendedLogger.warn({test:2});
 
+    assume(logs[0]||[]).is.eql([{test:1}]);
+    assume(logs[1]||[]).is.eql([{message:{test:2},level:'warn'}]);
   });
 
   it('.add({ invalid Transport })', function () {