Jest/Typescript: Mock class 依赖包含 jest 和 typescript 中的私有成员

Question

上下文：我有 class B 依赖于 class A。我想测试 class B 的方法，它在内部调用 [=67= 的方法] A. 现在，我想通过模拟 class A.

来对 class B 的方法进行单元测试

注1: Class A有一些私有成员

注2:ClassA没有接口

这是我的代码结构：


class Base {

  someMethod() {
     return "Hello ";
  }

}


class A {

  private _baseClassImpl: Base;

  constructor(baseClassImpl: Base) {
     this._baseClassImpl = baseClassImpl;
  }

  getSomething() {     
     return this._baseClassImpl.someMethod() + " Something";
  }
}


class B {
  constructor(objectOfClassA: A) {
      this._objectOfClassA = objectOfClassA;

 }

 functionOfClassBToTest() {
     const returnValueFromClassA = this._objectOfClassA.getSomething();

     return returnValueFromClassA;
 }
}

到目前为止我已经尝试过：

在采纳了的建议后，我尝试编写如下测试：


const getSomethingMock = jest.fn().mockImplementation(() => {
    return "Mock value";
});

const mockA = jest.Mocked<A> = {
   getSomething: getSomethingMock
};

test("test functionOfClassBToTest", () => {
   const classBToTest = new B(mockA);
   
   expect(classBToTest.functionofClassBToTest.toStrictEqual("Hello Something");

});

上面的代码给我这个错误：

Type '{ getSomething: jest.Mock<any, any>; }' is not assignable is not assignable to type 'Mocked<A>'. 
Type '{ getSomething: jest.Mock<any, any>; }' is missing the following properties from type 'A': _baseClassImpl

并且当我尝试像这样为 _baseClassImpl 提供模拟值时：

const baseClassMock = jest.Mocked<Base> = {
  someMethod: jest.fn()
};

const getSomethingMock = jest.fn().mockImplementation(() => {
    return "Mock value";
});

const mockA = jest.Mocked<A> = {
   getSomething: getSomethingMock,
   _baseClassImpl: baseClassMock
};

打字稿给我这个错误：

Type '{ getSomething: jest.Mock<any, any>; _baseClassImpl: jest.Mocked<Base>; }' is not assignable is not assignable to type 'Mocked<A>'. 

Type '{ getSomething: jest.Mock<any, any>; _baseClassImpl: jest.Mocked<Base>; }' is not assignable is not assignable to type 'A'. 

Property '_baseClassImpl' is private in type 'A' but not in type '{ getSomething: jest.Mock<any, any>; _baseClassImpl: jest.Mocked<Base>; }'

我已经在我的上尝试了这个答案，但它在 class 与私人成员的情况下不起作用。

一些注意事项：

注1: Class A包含私有成员

注2:ClassA没有接口

注释 3: 我不想在我的测试函数中初始化 class A 的对象。我只想嘲笑 class.

Answer 1

在这个 github repo 的帮助下，我解决了这个问题。

参考代码如下：

测试 functionOfClassBToTest ：


//Note: this can be also written as : const mockA = new (<any>A)() as jest.Mocked<A>;
const mockA = new (<new () => A>A)() as jest.Mocked<A>;

mockA.getSomething = jest.fn();

test("test functionOfClassBToTest", () => {
   
   mockA.getSomething.mockReturnValueOnce("Hello Something");

   const classBToTest = new B(mockA);
   
   expect(classBToTest.functionofClassBToTest.toStrictEqual("Hello Something");

});

Jest/Typescript: Mock class 依赖包含 jest 和 typescript 中的私有成员

Jest/Typescript: Mock class dependencies containing private members in jest and typescript

javascript

typescript

unit-testing

jestjs

ts-jest