Pass log arguments to augment processor function

Author: cressie176

README.md

@@ -206,6 +206,15 @@ logger.info("How blissful it is, for one who has nothing");
 }
 ```
 
+The source function will be called with an object containing the following parameters
+
+| name    | type               | notes                                |
+| ------- | ------------------ | ------------------------------------ |
+| level   | Level              | The log level                        |
+| message | string             | The log message                      |
+| context | Object             | The log context                      |
+| record  | Object             | The log record prior to augmentation |
+
 ### buffer
 
 The buffer processor outputs the record as a buffer, optionally encoding it before doing so. For this processor to work, the record must previously have been converted to a string.

lib/processors/augment.js

@@ -4,8 +4,8 @@ module.exports = (params = {}) => {
 };
 
 function augmentFn(fn) {
-  return ({ record }) => {
-    return { ...record, ...fn() };
+  return ({ level, message, ctx, record }) => {
+    return { ...record, ...fn({ level, message, ctx, record }) };
   };
 }
 

test/processors/augment.test.js

@@ -12,6 +12,15 @@ describe('augment', () => {
       eq(result, { a: 'b', x: 'y' });
     });
 
+    it('should pass the log arguments to the supplied function', () => {
+      const source = ({ level, message, ctx, record }) => {
+        return { level, message, ctx, record };
+      };
+      const fn = augment({ source });
+      const result = fn({ level: 1, message: 2, ctx: 3, record: { a: 'b' } });
+      eq(result, { a: 'b', level: 1, message: 2, ctx: 3, record: { a: 'b' } });
+    });
+
     it('should prefer source to record', () => {
       const source = () => {
         return { x: 'y' };