Karma缓存未更新：设置nocache仍提供旧Web Worker文件

我的karma.conf.js配置如下：

config.set({
basePath: '',
frameworks: ['jasmine', '@angular-devkit/build-angular'],
plugins: [
  require('karma-jasmine'),
  require('karma-chrome-launcher'),
  require('karma-jasmine-html-reporter'),
  require('karma-coverage-istanbul-reporter'),
  require('@angular-devkit/build-angular/plugins/karma')
],
files: [
  { pattern: 'src/workers/**/*.worker', type: 'js', watched: true, included: false, nocache: true, served: true }
],
proxies: {
  '/workers/': '/base/src/workers/'
}, ... });

我有一个以ES2022编译的TypeScript Web Worker库，还有一个消费该Worker的服务库，测试时通过注入令牌配置Worker实例：

{
    provide: ProxyWorkerToken,
    useFactory: () => {
      const url = new URL('http://localhost:9876/workers/identity.worker.js');
      if (url) {
        return new Worker(url, { 
          name: 'identity.worker',
          type: 'module' 
        });
      }
      throw new Error(`url is undefined, node_module path to worker could not be resolved.`);
    }
  }

最初Karma提供的identity.worker.js内容为：

export * from './subsonic-core-identity.worker';

但这与库打包生成的mjs文件不匹配，我将文件内容修改为：

export * from './subsonic-core-identity.worker.mjs';

然而Karma开发服务器仍返回旧版文件，我已尝试清理浏览器缓存、确认nocache设为true、重启电脑、清除Chrome缓存，但均无效。直接加载mjs文件时Worker能正常创建。

附身份库的angular.json配置：

"@subsonic-core/identity": {
  "projectType": "library",
  "root": "projects/subsonic-core/identity",
  "sourceRoot": "projects/subsonic-core/identity/src",
  "prefix": "lib",
  "architect": {
    "build": {
      "builder": "@angular-devkit/build-angular:ng-packagr",
      "options": {
        "project": "projects/subsonic-core/identity/ng-package.json"
      },
      "configurations": {
        "production": {
          "tsConfig": "projects/subsonic-core/identity/tsconfig.lib.prod.json"
        },
        "development": {
          "tsConfig": "projects/subsonic-core/identity/tsconfig.lib.json"
        }
      },
      "defaultConfiguration": "production"
    },
    "test": {
      "builder": "@angular-devkit/build-angular:karma",
      "options": {
        "tsConfig": "projects/subsonic-core/identity/tsconfig.spec.json",
        "assets": [
          {
            "glob": "**/*",
            "input": "./node_modules/@subsonic-core/identity.worker/fesm2022",
            "output": "./workers"
          }
        ],
        "polyfills": [
          "zone.js",
          "zone.js/testing"
        ],
        "scripts": []
      }
    }
  }
}

按优先级尝试以下方法：

• 清除Karma本地缓存目录
  Karma会在项目根目录的./.karma或./node_modules/.cache/karma存储缓存，直接删除这些目录后重启Karma。

• 更新测试资产配置与Worker库
  先重新构建Worker库确保node_modules下的文件是最新的：

  ng build @subsonic-core/identity.worker
  

  再修改angular.json的测试assets配置，指定加载你修改后的本地identity.worker.js，而非从node_modules复制的旧文件：

  "assets": [
    {
      "glob": "**/*.mjs",
      "input": "./node_modules/@subsonic-core/identity.worker/fesm2022",
      "output": "./workers"
    },
    {
      "glob": "identity.worker.js",
      "input": "./src/workers",
      "output": "./workers"
    }
  ]
  

• 调整Karma的files配置优先级
  在karma.conf.js的files数组中，将修改后的identity.worker.js放在通配符规则前面，确保优先加载：

  files: [
    { pattern: 'src/workers/identity.worker.js', type: 'js', watched: true, included: false, nocache: true, served: true },
    { pattern: 'src/workers/**/*.worker', type: 'js', watched: true, included: false, nocache: true, served: true }
  ]
  

• 彻底关闭Karma缓存
  在karma.conf.js中添加全局缓存禁用配置：

  config.set({
    // ...其他配置
    cache: false,
    // ...
  });
  

• 临时添加URL版本戳
  在Worker的请求URL后添加时间戳参数，强制绕过缓存：

  const url = new URL('http://localhost:9876/workers/identity.worker.js?v=' + Date.now());
  

内容的提问来源于stack exchange，提问作者Kenneth Carter