使用Jest测试NestJS应用时出现cache-manager包缺失错误

我使用@nestjs/cache-manager和cache-manager包实现了NestJS应用的缓存功能，应用本身运行正常，但用Jest进行测试时出现了cache-manager包缺失的报错：

ERROR [PackageLoader] The "cache-manager" package is missing. Please, make sure to install this library ($ npm install cache-manager) to take advantage of CacheModule.
  ●  process.exit called with "1"

      at loadPackage (../node_modules/@nestjs/common/utils/load-package.util.js:14:17)
      at InstanceWrapper.useFactory [as metatype] (../node_modules/@nestjs/cache-manager/dist/cache.providers.js:18:70)
      at TestingInjector.instantiateClass (../node_modules/@nestjs/core/injector/injector.js:354:55)
      at callback (../node_modules/@nestjs/core/injector/injector.js:56:45)
      at TestingInjector.resolveConstructorParams (../node_modules/@nestjs/core/injector/injector.js:136:24)
      at TestingInjector.loadInstance (../node_modules/@nestjs/core/injector/injector.js:61:13)
      at TestingInjector.loadProvider (../node_modules/@nestjs/core/injector/injector.js:88:9)
      at ../node_modules/@nestjs/core/injector/instance-loader.js:56:13
          at async Promise.all (index 3)

相关配置片段 #

package.json依赖部分

"dependencies": {
    "@nest-modules/mailer": "^1.1.3",
    "@nestjs/cache-manager": "^2.2.0",
    "@nestjs/common": "^9.4.3",
    "@nestjs/core": "^9.4.3",
    "@nestjs/jwt": "^10.0.1",
    "@nestjs/passport": "^6.1.0",
    "@nestjs/platform-express": "^9.4.3",
    "@nestjs/schedule": "^0.4.3",
    "@nestjs/serve-static": "^2.2.2",
    "@types/nodemailer": "^6.4.4",
    "JSONStream": "^1.3.5",
    "ajv": "^6.12.6",
    "argon2": "^0.30.3",
    "cache-manager": "^5.4.0",
    "bcryptjs": "^2.4.3",
    "chalk": "^2.4.2",
    "class-transformer": "^0.3.1",
    "class-validator": "^0.14.0",
    "csv-parser": "^3.0.0",
    "exceljs": "^4.3.0",
    "faker": "^4.1.0",
    "handlebars": "^4.7.7",
    "hashids": "^2.0.0",
    "inquirer": "^7.0.0",
    "jest-junit": "^8.0.0",
    "js-joda": "^1.11.0",
    "json2csv": "^5.0.6",
    "knex": "^0.21.1",
    "nodemailer": "^6.7.2",
    "npm": "^8.19.2",
    "passport": "^0.6.0",
    "passport-jwt": "^4.0.1",
    "pg": "^8.9.0",
    "pg-query-stream": "^4.2.3",
    "pkg-dir": "^4.2.0",
    "ramda": "^0.26.1",
    "reflect-metadata": "^0.1.13",
    "remove-accents": "^0.4.2",
    "rimraf": "^3.0.0",
    "shelljs": "^0.8.5",
    "sinon": "^13.0.1",
    "stream-json": "^1.7.4",
    "ts-loader": "^6.0.4",
    "ts-node": "^8.3.0",
    "tsconfig-paths": "^3.8.0",
    "typescript": "^3.6.2",
    "xlsx": "^0.17.1",
    "yargs-parser": "^21.0.1"
  },
  "devDependencies": {
    "@nestjs/testing": "^9.4.3",
    "@types/bcryptjs": "^2.4.2",
    "@types/cron": "^1.7.2",
    "@types/dotenv": "^6.1.1",
    "@types/express": "^4.17.1",
    "@types/faker": "^4.1.5",
    "@types/inquirer": "^6.5.0",
    "@types/jest": "^29.5.11",
    "@types/knex": "^0.16.1",
    "@types/node": "^12.7.4",
    "@types/nodemailer": "^6.4.4",
    "@types/pg": "^7.11.1",
    "@types/puppeteer": "^1.19.1",
    "@types/rimraf": "^2.0.2",
    "@types/shelljs": "^0.8.5",
    "@types/supertest": "^2.0.8",
    "chalk": "^2.4.2",
    "faker": "^4.1.0",
    "inquirer": "^7.0.0",
    "jest": "^24.9.0",
    "nodemon": "^2.0.19",
    "prettier": "^1.18.2",
    "rimraf": "^3.0.0",
    "shelljs": "^0.8.5",
    "supertest": "^4.0.2",
    "ts-jest": "^24.0.2",
    "ts-loader": "^6.0.4",
    "ts-node": "^8.3.0",
    "tsconfig-paths": "^3.8.0",
    "tslint": "5.19.0",
    "tslint-config-prettier": "^1.18.0",
    "typescript": "^3.6.2",
    "webpack": "^4.39.3",
    "webpack-cli": "^3.3.7",
    "webpack-node-externals": "^1.7.2"
  }

测试代码配置

import { CacheModule, CACHE_MANAGER } from '@nestjs/cache-manager';
import { HttpServer, INestApplication } from '@nestjs/common';
import { Test } from '@nestjs/testing';
import * as request from 'supertest';

import { AppModule } from '../../../src/app.module';
import { getAuthorizationHeaders } from '../../../test/e2e.utils';
import { SessionModule } from '../session/session.module';

import { PreferencesModule } from './preferences.module';

describe('Preferences (e2e)', () => {
  let app: INestApplication;
  let server: HttpServer;
  let serverRequest;
  let authorizationHeaders;

  beforeAll(async () => {
    const moduleFixture = await Test.createTestingModule({
      imports: [PreferencesModule, SessionModule, CacheModule],
      providers: [{ provide: CACHE_MANAGER, useValue: {} }]
    }).compile();

    app = moduleFixture.createNestApplication();
    await app.init();
    server = await app.getHttpServer();
    serverRequest = await request(server);
    authorizationHeaders = await getAuthorizationHeaders(serverRequest);
  });

排查与修复方案 #

• 问题核心原因
  尽管你已经在生产依赖中安装了cache-manager，但测试模块中直接导入未配置的CacheModule时，@nestjs/cache-manager会触发动态加载逻辑检查cache-manager包是否存在。同时，你虽然提供了CACHE_MANAGER的模拟实现，但模块初始化顺序导致包检查在模拟注入前执行，从而抛出错误。

• 修复方案1：配置CacheModule跳过缓存工厂初始化
  在测试模块导入CacheModule时，添加skipCacheFactory: true配置，跳过默认的缓存工厂创建流程，避免触发包检查：

  const moduleFixture = await Test.createTestingModule({
    imports: [
      PreferencesModule, 
      SessionModule, 
      CacheModule.register({
        skipCacheFactory: true
      })
    ],
    providers: [{ provide: CACHE_MANAGER, useValue: {} }]
  }).compile();
  

• 修复方案2：移除CacheModule导入，仅保留模拟服务
  既然已经手动提供了CACHE_MANAGER的模拟实现，若PreferencesModule和SessionModule仅依赖CACHE_MANAGER服务而非CacheModule本身，可以直接移除CacheModule的导入，只保留模拟提供者：

  const moduleFixture = await Test.createTestingModule({
    imports: [PreferencesModule, SessionModule],
    providers: [{ provide: CACHE_MANAGER, useValue: {} }]
  }).compile();
  

• 额外验证步骤

  • 执行npm ls cache-manager确认node_modules中确实存在该包
  • 若使用pnpm/yarn等包管理器，可尝试删除node_modules和锁文件后重新执行npm install，排除依赖安装缓存问题

内容的提问来源于stack exchange，提问作者Princeton Ebanks