fix: log everything to stderr, not stdout (#321)

Author: akx

src/defaultLogger.ts

@@ -0,0 +1,13 @@
+// tslint:disable:no-console
+import { Logger } from '.';
+
+const defaultLogger: Logger = {
+  // since `console.warn` is an alias to `console.error`,
+  // and `console.error` is really only a `console.info` for stderr
+  // instead of stdout, these are all equivalent by default.
+  error: console.error,
+  warn: console.error,
+  info: console.error
+};
+
+export default defaultLogger;

src/index.ts

@@ -16,6 +16,7 @@ import { createDefaultFormatter } from './formatter/defaultFormatter';
 import { createCodeframeFormatter } from './formatter/codeframeFormatter';
 import { fileExistsSync } from './FsHelper';
 import { Message } from './Message';
+import defaultLogger from './defaultLogger';
 
 import {
   getForkTsCheckerWebpackPluginHooks,
@@ -164,7 +165,7 @@ class ForkTsCheckerWebpackPlugin {
     this.ignoreLints = options.ignoreLints || [];
     this.ignoreLintWarnings = options.ignoreLintWarnings === true;
     this.reportFiles = options.reportFiles || [];
-    this.logger = options.logger || console;
+    this.logger = options.logger || defaultLogger;
     this.silent = options.silent === true; // default false
     this.async = options.async !== false; // default true
     this.checkSyntacticErrors = options.checkSyntacticErrors === true; // default false

test/integration/general.spec.ts

@@ -2,6 +2,7 @@
 import fs from 'fs';
 import path from 'path';
 import ForkTsCheckerWebpackPlugin from '../../lib/index';
+import defaultLogger from '../../lib/defaultLogger';
 import * as helpers from './helpers';
 import { cloneDeep } from 'lodash';
 import unixify from 'unixify';
@@ -49,10 +50,10 @@ describe.each([[true], [false]])(
       expect(plugin['tslint']).toBe(true);
     });
 
-    it('should set logger to console by default', () => {
+    it('should set logger to the default logger by default', () => {
       const plugin = new ForkTsCheckerWebpackPlugin({});
 
-      expect(plugin['logger']).toBe(console);
+      expect(plugin['logger']).toBe(defaultLogger);
     });
 
     it('should set watch to empty array by default', () => {