使用Jest+Expo+Firebase做集成测试时getFirestore函数报错

在Expo应用的登录页面执行Jest集成测试时，出现错误：TypeError: (0 , _firestore.getFirestore) is not a function。应用本身运行正常，getFirestore函数能被正常识别，但在Jest测试环境下却无法识别。怀疑是因为Firebase配置使用了Expo要求的Web Version 9导致的，尝试过以下几种导入方式均无效：

• import { firestore } from "firebase/firestore"
• import "firebase/firestore"
• export const db = app.firestore()

相关代码 #

Firebase配置文件 #

import { initializeApp } from 'firebase/app';
import { getFirestore } from "firebase/firestore";

// Firebase API
const firebaseConfig = {

  };

const app = initializeApp(firebaseConfig);
export const db = getFirestore(app);

package.json #

{
  "name": "test",
  "version": "1.0.0",
  "main": "node_modules/expo/AppEntry.js",
  "scripts": {
    "start": "expo start",
    "android": "expo start --android",
    "ios": "expo start --ios",
    "web": "expo start --web"
  },
  "dependencies": {
    "@emailjs/browser": "^3.10.0",
    "@expo/dev-server": "0.1.120",
    "@expo/webpack-config": "^0.17.0",
    "@react-native-async-storage/async-storage": "~1.17.3",
    "@react-native-community/clipboard": "^1.5.1",
    "@react-native-community/datetimepicker": "6.5.2",
    "@react-native-community/masked-view": "^0.1.11",
    "@react-native-picker/picker": "2.4.8",
    "@react-navigation/bottom-tabs": "^6.4.0",
    "@react-navigation/native": "^6.0.13",
    "@react-navigation/stack": "^6.3.3",
    "@twotalltotems/react-native-otp-input": "1.3.7",
    "base-64": "^1.0.0",
    "expo": "^47.0.8",
    "expo-checkbox": "~2.2.0",
    "expo-document-picker": "~11.0.1",
    "expo-image-picker": "~14.0.2",
    "expo-location": "~15.0.1",
    "expo-status-bar": "~1.4.0",
    "expo-web-browser": "~12.0.0",
    "firebase": "^9.16.0",
    "jest": "^26.6.3",
    "jest-expo": "^47.0.1",
    "leo-profanity": "^1.7.0",
    "lottie-react-native": "^5.1.4",
    "moment": "^2.29.4",
    "parse": "^4.0.0",
    "react": "18.1.0",
    "react-dom": "18.1.0",
    "react-hook-form": "^7.42.0",
    "react-native": "0.70.5",
    "react-native-draggable-flatlist": "^4.0.0",
    "react-native-dropdown-select-list": "^2.0.4",
    "react-native-gesture-handler": "~2.8.0",
    "react-native-google-places-autocomplete": "^2.5.1",
    "react-native-keyboard-aware-scroll-view": "^0.9.5",
    "react-native-keychain": "^8.1.1",
    "react-native-maps": "1.3.2",
    "react-native-maps-directions": "^1.9.0",
    "react-native-modal-datetime-picker": "^14.0.1",
    "react-native-otp-input": "^1.0.12",
    "react-native-paper": "^4.12.5",
    "react-native-picker-select": "^8.0.4",
    "react-native-reanimated": "~2.12.0",
    "react-native-reanimated-carousel": "^3.1.5",
    "react-native-safe-area-context": "4.4.1",
    "react-native-screens": "~3.18.0",
    "react-native-uuid": "^2.0.1",
    "react-native-web": "~0.18.7",
    "react-native-webview": "11.23.1",
    "rn-credit-card": "^1.0.4",
    "uniqid": "^5.4.0"
  },
  "devDependencies": {
    "@babel/core": "^7.12.9",
    "@testing-library/react-native": "^11.5.1"
  },
  "jest": {
    "preset": "jest-expo",
    "transformIgnorePatterns": [
      "node_modules/(?!((jest-)?react-native|@react-native(-community)?)|expo(nent)?|@expo(nent)?/.*|@expo-google-fonts/.*|react-navigation|@react-navigation/.*|@unimodules/.*|unimodules|sentry-expo|native-base|react-native-svg)"
    ]
  },
  "private": true
}

解决方案 #

1. 调整Jest的transformIgnorePatterns #

当前的transformIgnorePatterns未包含Firebase相关模块，导致Jest没有转译Firebase v9的ES模块语法。修改jest配置，添加firebase和@firebase到白名单：

"jest": {
  "preset": "jest-expo",
  "transformIgnorePatterns": [
    "node_modules/(?!((jest-)?react-native|@react-native(-community)?)|expo(nent)?|@expo(nent)?/.*|@expo-google-fonts/.*|react-navigation|@react-navigation/.*|@unimodules/.*|unimodules|sentry-expo|native-base|react-native-svg|firebase|@firebase)"
  ]
}

2. 模拟Firestore模块 #

直接在测试中模拟Firestore模块，避免调用真实Firebase API。创建__mocks__/firebase/firestore.js文件：

export const getFirestore = jest.fn(() => ({
  // 按需模拟Firestore方法，比如collection、doc等
  collection: jest.fn(() => ({
    add: jest.fn(),
    get: jest.fn()
  }))
}));

然后在测试文件顶部添加：

jest.mock('firebase/firestore');

3. 降级Firebase版本（不推荐） #

如果以上方法无效，可尝试降级到Firebase v8兼容版本，但可能与Expo要求冲突，需谨慎操作。

内容的提问来源于stack exchange，提问作者Ivan