Add timestamp to json format

package.json

@@ -51,14 +51,14 @@
     "email": "[email protected]"
   },
   "devDependencies": {
-    "@types/jest": "^29.2.5",
+    "@types/jest": "^29.5.14",
     "@types/node": "^18.13.0",
     "@typescript-eslint/eslint-plugin": "^5.48.1",
     "@typescript-eslint/parser": "^5.48.1",
     "eslint": "^8.34.0",
-    "jest": "^29.4.3",
-    "ts-jest": "^29.0.4",
+    "jest": "^29.7.0",
+    "ts-jest": "^29.2.5",
     "ts-mockito": "^2.6.1",
     "typescript": "^4.9.4"
   }
-}
+}

src/formats/json.format.spec.ts

@@ -0,0 +1,28 @@
+import { JsonFormat, JsonFormatOptions } from './json.format'
+import { Log } from '../log'
+import { Level } from '../level'
+
+describe('JsonFormat', () => {
+  describe('when log has timestamp set to epoch timestamp', () => {
+    it('it includes the timestamp attribute formatted as ISO-8601 with UTC timezone', () => {
+      const timestamp = 1731912859428
+      const log: Log = {
+        level: Level.INFO,
+        message: '',
+        timestamp,
+      }
+      const testee: JsonFormat = createTestee()
+
+      const result: string = testee.apply(log)
+
+      expect(result).toMatch('"timestamp":"2024-11-18T06:54:19.428Z"')
+    })
+  })
+})
+
+function createTestee(options: Partial<JsonFormatOptions> = {}): JsonFormat {
+  return new JsonFormat({
+    isPretty: false,
+    ...options,
+  })
+}

src/formats/json.format.ts

@@ -1,6 +1,8 @@
 import { Format } from '../format'
 import { Log } from '../log'
 import { JsonEncoder } from '../services/json-encoder'
+import { DateFormatter } from '../services/date-formatter'
+import { IsoDateFormatter } from '../services/iso-date-formatter'
 
 export interface JsonFormatOptions {
   isPretty: boolean
@@ -9,14 +11,29 @@ export interface JsonFormatOptions {
 export class JsonFormat extends Format {
 
   private readonly jsonEncoder: JsonEncoder
+  private readonly dateFormatter: DateFormatter
 
   constructor(options: JsonFormatOptions) {
     super()
     this.jsonEncoder = new JsonEncoder(options)
+    this.dateFormatter = new IsoDateFormatter()
   }
 
-  apply(log: Log): string {
-    return this.jsonEncoder.encode(log)
+  public apply(log: Log): string {
+    return this.jsonEncoder.encode({
+      ...log,
+      timestamp: this.getFormattedTimestamp(log.timestamp)
+    })
+  }
+
+  private getFormattedTimestamp(timestamp: unknown): string {
+    if (typeof timestamp === 'number') {
+      return this.dateFormatter.formatTimestamp(timestamp)
+    }
+    if (!timestamp) {
+      return this.dateFormatter.formatTimestamp(Date.now())
+    }
+    return `${timestamp}`
   }
 
 }

src/formats/plain-text.format.ts

@@ -26,9 +26,13 @@ export class PlainTextFormat extends Format {
   }
 
   protected getTimestamp(log: Log): string {
-    const timestamp = log.timestamp ?? Date.now()
-    const formattedTimestamp = this.dateFormatter.formatTimestamp(timestamp)
-    return `[${ formattedTimestamp }]`
+    if (typeof log.timestamp === 'number') {
+      return `[${this.dateFormatter.formatTimestamp(log.timestamp)}]`
+    }
+    if (!log.timestamp) {
+      return `[${this.dateFormatter.formatTimestamp(Date.now())}]`
+    }
+    return `[${ log.timestamp }]`
   }
 
   protected getSeverity(log: Log): string {

src/log.ts

@@ -3,6 +3,5 @@ import { Level } from './level'
 export interface Log {
   level: Level,
   message: unknown,
-  timestamp?: number,
   [key: string]: unknown,
 }

src/logger-base.ts

@@ -35,6 +35,7 @@ export class LoggerBase extends Logger {
 
   private log(message: unknown, level: Level, metadata: object): void {
     const log: Log = {
+      timestamp: Date.now(),
       ...metadata,
       level,
       message,