Improve Logging (#1519)

Improve Logging

Signed-off-by: Tilman Vatteroth <git@tilmanvatteroth.de>

src/utils/logger.test.ts

@@ -0,0 +1,71 @@
+/*
+ * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { Logger, LogLevel } from './logger'
+import { Settings } from 'luxon'
+
+describe('Logger', () => {
+  let consoleMock: jest.SpyInstance
+  let originalNow: () => number
+  let dateShift = 0
+
+  function mockConsole(methodToMock: LogLevel, onResult: (result: string) => void) {
+    consoleMock = jest.spyOn(console, methodToMock).mockImplementation((...data: string[]) => {
+      const result = data.reduce((state, current) => state + ' ' + current)
+      onResult(result)
+    })
+  }
+
+  beforeEach(() => {
+    originalNow = Settings.now
+    Settings.now = () => new Date(2021, 9, 25, dateShift, 1 + dateShift, 2 + dateShift, 3 + dateShift).valueOf()
+  })
+
+  afterEach(() => {
+    Settings.now = originalNow
+    consoleMock.mockReset()
+  })
+
+  it('logs a debug message into the console', (done) => {
+    dateShift = 0
+    mockConsole(LogLevel.DEBUG, (result) => {
+      expect(consoleMock).toBeCalled()
+      expect(result).toEqual('%c[2021-10-25 00:01:02] %c(prefix) color: yellow color: orange beans')
+      done()
+    })
+    new Logger('prefix').debug('beans')
+  })
+
+  it('logs a info message into the console', (done) => {
+    dateShift = 1
+    mockConsole(LogLevel.INFO, (result) => {
+      expect(consoleMock).toBeCalled()
+      expect(result).toEqual('%c[2021-10-25 01:02:03] %c(prefix) color: yellow color: orange toast')
+      done()
+    })
+    new Logger('prefix').info('toast')
+  })
+
+  it('logs a warn message into the console', (done) => {
+    dateShift = 2
+    mockConsole(LogLevel.WARN, (result) => {
+      expect(consoleMock).toBeCalled()
+      expect(result).toEqual('%c[2021-10-25 02:03:04] %c(prefix) color: yellow color: orange eggs')
+      done()
+    })
+    new Logger('prefix').warn('eggs')
+  })
+
+  it('logs a error message into the console', (done) => {
+    dateShift = 3
+    mockConsole(LogLevel.ERROR, (result) => {
+      expect(consoleMock).toBeCalled()
+      expect(result).toEqual('%c[2021-10-25 03:04:05] %c(prefix) color: yellow color: orange bacon')
+      done()
+    })
+    new Logger('prefix').error('bacon')
+  })
+})

src/utils/logger.ts

@@ -0,0 +1,83 @@
+/*
+ * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import { DateTime } from 'luxon'
+
+export enum LogLevel {
+  DEBUG = 'debug',
+  INFO = 'info',
+  WARN = 'warn',
+  ERROR = 'error'
+}
+
+type OutputFunction = (...data: unknown[]) => void
+
+/**
+ * Simple logger that prefixes messages with a timestamp and a name
+ */
+export class Logger {
+  private readonly scope: string
+
+  constructor(scope: string) {
+    this.scope = scope
+  }
+
+  /**
+   * Logs a debug message
+   * @param data data to log
+   */
+  debug(...data: unknown[]): void {
+    this.log(LogLevel.DEBUG, ...data)
+  }
+
+  /**
+   * Logs a normal informative message
+   * @param data data to log
+   */
+  info(...data: unknown[]): void {
+    this.log(LogLevel.INFO, ...data)
+  }
+
+  /**
+   * Logs a warning
+   * @param data data to log
+   */
+  warn(...data: unknown[]): void {
+    this.log(LogLevel.WARN, ...data)
+  }
+
+  /**
+   * Logs an error
+   * @param data data to log
+   */
+  error(...data: unknown[]): void {
+    this.log(LogLevel.ERROR, ...data)
+  }
+
+  private log(loglevel: LogLevel, ...data: unknown[]) {
+    const preparedData = [...this.prefix(), ...data]
+    const logOutput = Logger.getLogOutput(loglevel)
+    logOutput(...preparedData)
+  }
+
+  private static getLogOutput(logLevel: LogLevel): OutputFunction {
+    switch (logLevel) {
+      case LogLevel.INFO:
+        return console.info
+      case LogLevel.DEBUG:
+        return console.debug
+      case LogLevel.ERROR:
+        return console.error
+      case LogLevel.WARN:
+        return console.warn
+    }
+  }
+
+  private prefix(): string[] {
+    const timestamp = DateTime.now().toFormat('yyyy-MM-dd HH:mm:ss')
+    return [`%c[${timestamp}] %c(${this.scope})`, 'color: yellow', 'color: orange']
+  }
+}