Print log levels in different colors

packages/logger-pretty/lib/LoggerPretty.ts

@@ -7,10 +7,18 @@ const process: NodeJS.Process = require('process/');
  * A logger that pretty-prints everything.
  */
 export class LoggerPretty extends Logger {
+  public static readonly COLOR_RESET: string = '\u001B[0m';
+  public static readonly COLOR_RED: string = '\u001B[31m';
+  public static readonly COLOR_GREEN: string = '\u001B[32m';
+  public static readonly COLOR_YELLOW: string = '\u001B[33m';
+  public static readonly COLOR_BLUE: string = '\u001B[34m';
+  public static readonly COLOR_MAGENTA: string = '\u001B[35m';
+  public static readonly COLOR_CYAN: string = '\u001B[36m';
+  public static readonly COLOR_GRAY: string = '\u001B[90m';
+
   private readonly level: string;
   private readonly levelOrdinal: number;
   private readonly actors?: Record<string, boolean>;
-
   public constructor(args: ILoggerPrettyArgs) {
     super();
     this.level = args.level;
@@ -19,35 +27,44 @@ export class LoggerPretty extends Logger {
   }
 
   public debug(message: string, data?: any): void {
-    this.log('debug', message, data);
+    this.log('debug', LoggerPretty.COLOR_GRAY, message, data);
   }
 
   public error(message: string, data?: any): void {
-    this.log('error', message, data);
+    this.log('error', LoggerPretty.COLOR_RED, message, data);
   }
 
   public fatal(message: string, data?: any): void {
-    this.log('fatal', message, data);
+    this.log('fatal', LoggerPretty.COLOR_CYAN, message, data);
   }
 
   public info(message: string, data?: any): void {
-    this.log('info', message, data);
+    this.log('info', LoggerPretty.COLOR_GREEN, message, data);
   }
 
   public trace(message: string, data?: any): void {
-    this.log('trace', message, data);
+    this.log('trace', LoggerPretty.COLOR_BLUE, message, data);
   }
 
   public warn(message: string, data?: any): void {
-    this.log('warn', message, data);
+    this.log('warn', LoggerPretty.COLOR_YELLOW, message, data);
   }
 
-  protected log(level: string, message: string, data?: any): void {
+  protected log(level: string, color: string, message: string, data?: any): void {
     if (Logger.getLevelOrdinal(level) >= this.levelOrdinal &&
       (!data || !('actor' in data) || !this.actors || this.actors[data.actor])) {
-      process.stderr.write(`[${new Date().toISOString()}]  ${level.toUpperCase()}: ${message} ${objectInspect(data)}\n`);
+      process.stderr.write(LoggerPretty.withColor(`[${new Date().toISOString()}]  ${level.toUpperCase()}: ${message} ${objectInspect(data)}\n`, color));
     }
   }
+
+  /**
+   * Return a string in a given color
+   * @param str The string that should be printed in
+   * @param color A given color
+   */
+  public static withColor(str: any, color: string): string {
+    return `${color}${str}${LoggerPretty.COLOR_RESET}`;
+  }
 }
 
 export interface ILoggerPrettyArgs {