#31: updates logging module to allow multiple arguments and data type…

lib/log.js

@@ -1,20 +1,42 @@
 const {createLogger, format, transports} = require('winston')
+const util = require('util')
 
 module.exports = (file) => {
     const logger = createLogger({
         format: format.combine(
             format.timestamp({format:'YYYY-MM-DD HH:mm:ss'}),
             format.label({
-                label: file
+                label: file.split(/(\\|\/)/g).pop()
             }),
             format.colorize(),
-            format.printf(
-                info => `${info.timestamp} ${info.level} [${info.label}]: ${info.message}`
-            )
+            format.printf((info) => {
+                    return `${info.timestamp} ${info.level} [${info.label}]: ${info.message}`
+                })
         ),
         transports : [
             new transports.Console()
         ]
     })
-    return logger        
+
+    const processArgs = (args) => {
+        const mappedArgs = args.map((e) => {
+            if (e instanceof Error) return e.toString()
+            return e
+        })
+        return util.format('%j', mappedArgs)
+    }
+
+    const obj = {
+        info: (...args) => {
+            logger.info(processArgs(args))
+        },
+        warn: (...args) => {
+            logger.warn(processArgs(args))
+        },
+        error: (...args) => {
+            logger.error(processArgs(args))
+        }
+    }
+
+    return obj        
 }

lib/log.test.js

@@ -1,11 +1,46 @@
 const winston = require('winston')
-winston.createLogger = jest.fn()
+const util = require('util')
+
+winston.createLogger = jest.fn().mockReturnValue({
+    info: () => {},
+    warn: () => {},
+    error: () => {}
+})
+
+winston.format = {
+    combine: () => {},
+    timestamp: () => {},
+    label: () => {},
+    colorize: () => {},
+    printf: jest.fn()
+}
+
+util.format = jest.fn()
+
 describe('Testing log.js', () => {
     beforeEach(() => {
         jest.clearAllMocks()
     })
+    it('should call util.format everytime when log.xxx is called', () => {
+        const logger = require('./log')(__filename)
+        logger.info('message', [0,1,2])
+        logger.warn('message', {obj: () => {}})
+        logger.error('message', new Error('error message'))
+        expect(util.format).toHaveBeenCalled()
+    })
     it('should call winston.createLogger when log is required', () => {
         const logger = require('./log')(__filename)
         expect(winston.createLogger).toHaveBeenCalled()
     })
+    it('should return log string correctly', () => {
+        const logger = require('./log')(__filename)
+        const argInPrintf = winston.format.printf.mock.calls[0][0]
+        const testData = {
+            timestamp: "2020-04-30 22:43:00",
+            level: "info",
+            label: "log.test.js",
+            message: "message"
+        }
+        expect(argInPrintf(testData)).toBe("2020-04-30 22:43:00 info [log.test.js]: message")
+    })
 })