javascript - es6协作者的模拟构建

Question

我有一个利用辅助类的类，我想验证它是否正确构造了这些对象。所以，我试图在我的类中 stub “构造函数”方法，但我显然做得不对:

"use strict";

class Collaborator {
  constructor(settings) {
    console.log("Don't want this to be called!")
    this.settings = settings;
  }
}

class ThingToTest {
  constructor(settings) {
    this.helper = new Collaborator(settings);
  }
}

const assert = require("assert");
const sinon = require("sinon");

describe("ThingToTest", () => {
  let settings = "all the things"

  context("spying on constructor", () => {
    let spy = sinon.spy(Collaborator, "constructor")
    after(() => spy.restore()) 
    describe("constructor", () => {
      it("creates a Collaborator with provided settings", () => {
        new ThingToTest(settings);
        sinon.assert.calledWith(spy, settings)
      })
    })
  })

  context("spying on prototype constructor", () => {
    let spy = sinon.spy(Collaborator.prototype, "constructor")
    after(() => spy.restore()) 
    describe("constructor", () => {
      it("creates a Collaborator with provided settings", () => {
        new ThingToTest(settings);
        sinon.assert.calledWith(spy, settings)
      })
    })
  })

  context("stub constructor", () => {
    before(() => {
      sinon.stub(Collaborator, "constructor", (settings) => {
        console.log("This should be called so we can inspect", settings);
      })
    })
    after(() => { Collaborator.constructor.restore() }) 
    describe("constructor", () => {
      it("creates a Collaborator with provided settings", () => {
        new ThingToTest(settings);
      })
    })
  })

  context("stub prototype constructor", () => {
    before(() => {
      sinon.stub(Collaborator.prototype, "constructor", (settings) => {
        console.log("This should be called so we can inspect", settings);
      })
    })
    after(() => { Collaborator.prototype.constructor.restore() }) 
    describe("constructor", () => {
      it("creates a Collaborator with provided settings", () => {
        new ThingToTest(settings);
      })
    })
  })

})

运行此命令会产生这些(不需要的)结果:

ThingToTest
    spying on constructor
      constructor
Don't want this to be called!
        1) creates a Collaborator with provided settings
    spying on prototype constructor
      constructor
Don't want this to be called!
        2) creates a Collaborator with provided settings
    stub constructor
      constructor
Don't want this to be called!
        ✓ creates a Collaborator with provided settings
    stub prototype constructor
      constructor
Don't want this to be called!
        ✓ creates a Collaborator with provided settings

似乎 stub 是有效的，因为将 stub 测试放在 spy 测试错误之前，并出现可怕的“TypeError:试图包装已经包装的构造函数”。因此，清楚地弄清楚如何模拟 Collaborators 构造函数只是我做错的事情的一半。 。 。我也没有正确恢复构造函数。有什么建议吗？

Answer 1

这不是我想要的解决方案，但是目前我可能最终会使用它(但是请，如果您有建议，请救救我):

context("checking Collaborator in a more integration style test", () => {
    describe("constructor", () => {
      it("creates a Collaborator with provided settings", () => {
        let thing = new ThingToTest(settings);
        assert.equal(thing.helper.settings, settings)
      })
    })
  })

这将通过并验证协作者是否设置了正确的设置。但现在如果我想重构 Collaborator 构造函数，我将破坏 ThingToTest。再次强调，我仍然希望有人能提出一种方法来实际对此类进行单元测试!