Unable to create object of child class - TypeError: HomePage_1.HomePage is not a constructor

Question

我正在将 typescript 与 Protractor 和 mocha 一起使用。基本上尝试运行一个将经过多个页面的测试。我正在尝试使用 POM，但在使用继承时无法实例化对象。

当我尝试创建新对象时出现以下错误：

UnhandledPromiseRejectionWarning: TypeError: HomePage_1.HomePage is not a constructor

我可以实例化一个 class 的对象，但它不会从任何其他 class 扩展（下面的导航对象没有问题）。我在这里尝试了类似问题的各种建议，但其中 none 似乎有效。

这是我的测试class：e2e.ts

import { browser } from 'protractor';
import { Navigation } from './core/Navigation';
import { HomePage } from './page-objects/HomePage';

var nav = new Navigation(); // <-- SUCCESS NO PROBLEMS
var hmPg = new HomePage(); // <-- FAILS HERE
 describe('Add product to cart',async function() {
        it("start from homepage", async function() {
             nav.navigate("index");
        });

        it("Perform search", async function() {
              hmPg.search("monopoly board game");
        });

//some more tests here till adding the product to cart
});

首页class：HomePage.ts

import {browser, element, protractor} from 'protractor';
import { BasePageObject } from './BasePageObject';

export class HomePage extends BasePageObject{

    private EC = protractor.ExpectedConditions;
    private map;

    constructor(){
        super();
        super.loadMap(process.cwd()+"\page-objects\homePage.json");
    }

    public search(product:string){
       //some stuff here
    }

    //some more methods here.
}

这是我的 BasePageObject.ts class:

//some imports here
export class BasePageObject{

    //to store parsed json
    public mapData;
    public mapPath:string;
    public contentData;
    public contentPath:string;

    constructor(){
        //nothing to do here. Just setting the logger.
        log = factory.getLogger("BasePageObject");
    }
  //some other methods here
}

这是我的 tsconfig.json

{
  "compileOnSave": true,
  "compilerOptions": {
    "baseUrl": ".",
    "module": "commonjs",
    "paths": { "*": ["types/*"] },
    "outDir": "./dist/out-tsc",
    "mapRoot": "./dist/out-tsc/",
    "esModuleInterop": true,
    "sourceMap": true,
    "declaration": false,
    "moduleResolution": "node",
    "emitDecoratorMetadata": true,
    "experimentalDecorators": true,
    "allowSyntheticDefaultImports": true,
    "target": "es6",
    "typeRoots": [
      "node_modules/@types",
    ]
  }
}

这也是我测试运行ning tsc后生成的js文件class:

Object.defineProperty(exports, "__esModule", { value: true });
var protractor_1 = require("protractor");
var Navigation_1 = require("./core/Navigation");
var HomePage_1 = require("./page-objects/HomePage");

var nav = new Navigation_1.Navigation();
var hmPg = new HomePage_1.HomePage(); <--- FAILS HERE
describe('Add product to cart', function () {
    return __awaiter(this, void 0, void 0, function () {
        return __generator(this, function (_a) {
            this.timeout(90000);
            it("start from homepage", function () {
                return __awaiter(this, void 0, void 0, function () {
....
...
..
.

这是我在 package.json 中的依赖项：

"dependencies": {
    "@types/mocha": "^5.2.7",
    "@types/node": "^11.13.17",
    "chai": "^4.2.0",
    "chai-as-promised": "^7.1.1",
    "graphviz": "0.0.9",
    "minimist": "^1.2.0",
    "mocha": "^6.1.4",
    "npm-failsafe": "^0.4.1",
    "protractor": "^5.4.2",
    "protractor-screenshot-utils": "^1.0.3",
    "rimraf": "^2.6.3",
    "serenity-cli": "^0.11.3",
    "serenity-js": "^1.10.13",
    "ts-node": "^8.3.0",
    "tslint": "^5.18.0",
    "typescript": "^3.5.2",
    "typescript-logging": "^0.6.3",
    "yargs": "^13.2.4"
}

应该很简单，var obj = new Class()对吧？那不行。

Answer 1

题中包含的代码不够，看不出是什么问题。但是根据可以收集到的任何信息，您正在使用 async/await 并且量角器承诺管理器设置为 false。

如果是这种情况，那么预计您必须自己处理异步，无论是在构造函数、方法等中的任何地方。

该错误仅表示您在某处拥有本质上是异步的代码，并且未处理生成的 Promise。我建议查找作为 new HomePage().

的一部分执行的所有代码

此外，只需快速浏览一下代码，找出任何此类未处理承诺的情况。

希望对您有所帮助...

Unable to create object of child class - TypeError: HomePage_1.HomePage is not a constructor

Unable to create object of child class - TypeError: HomePage_1.HomePage is not a constructor

javascript

constructor

mocha.js

typescript

protractor