使用initializeTestApp时报错firebase__default.default.initializeApp is not a function

问题根因 #

该报错是ES模块与CommonJS模块互操作导致的导入异常，你使用的@firebase/rules-unit-testing 1.x版本没有默认导出，转译过程中错误将方法挂载到了default属性下，所以调用对应方法时找不到定义。

解决方案 #

• 调整导入语法，不要用import * as firebase的写法，直接按需导入所需方法：

// 修改导入部分
import { initializeTestApp, clearFirestoreData, loadFirestoreRules, assertFails } from "@firebase/rules-unit-testing";
import fs from "fs";
import path from "path";

对应方法调用不需要再带firebase.前缀，修改后的测试代码参考：

const myId = "user_Id";

// Load security rules
const filePath = path.join(__dirname, "./firestore.rules");
const rules = fs.readFileSync(filePath, "utf8");
const myProjectId = "my-project-2021";

describe("Allow access to users collection only when user is authorized", () => {
  beforeEach(
    async () => await clearFirestoreData({ projectId: myProjectId })
  );
  beforeEach(
    async () =>
      await loadFirestoreRules({
        projectId: myProjectId,
        rules: rules,
      })
  );

  afterAll(
    async () => await clearFirestoreData({ projectId: myProjectId })
  );

describe("allow access to project collection only when user is authorized", () => {
  test("fail to access without auth", async () => {
      const db = initializeTestApp({
          projectId: myProjectId,
        })
        .firestore();
      const doc = db
        .collection("users")
        .doc("user_shogo")
        .collection("projects")
        .doc("testProjectId");
      await assertFails(doc.get());
    });
  });
});

• 检查tsconfig.json配置，确保开启以下两个配置项：

{
  "compilerOptions": {
    "esModuleInterop": true,
    "allowSyntheticDefaultImports": true
  }
}

• 确认jest配置正确，使用ts-jest预设处理TypeScript文件，jest.config.js参考配置：

module.exports = {
  preset: 'ts-jest',
  testEnvironment: 'node',
  moduleFileExtensions: ['ts', 'tsx', 'js', 'jsx'],
  transform: {
    '^.+\\.tsx?$': 'ts-jest'
  }
};

操作完所有步骤后如果仍存在异常，可以删除node_modules目录后重新执行yarn install安装依赖，排除缓存问题。

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