如何用笑话测试“this”调用上下文?

开玩笑

创建 mock mock.instances to check the value of this .

test('the value of this using Jest', () => {
  const foo = {
    name: 'foo',
    func: function() {
      return `my name is ${this.name}`;
    }
  }
  const mockFunc = jest.spyOn(foo, 'func'); // spy on foo.func()

  expect(foo.func()).toBe('my name is foo');
  expect(mockFunc.mock.instances[0]).toBe(foo); // called on foo

  mockFunc.mockClear();

  const bar = {
    name: 'bar',
    func: foo.func // use the func from foo
  }

  expect(bar.func()).toBe('my name is bar');
  expect(mockFunc.mock.instances[0]).toBe(bar); // called on bar
});

西农

Sinon 提供直接访问 这 thisValue .

import * as sinon from 'sinon';

test('the value of this using Sinon', () => {
  const foo = {
    name: 'foo',
    func: function() {
      return `my name is ${this.name}`;
    }
  }
  const spy = sinon.spy(foo, 'func'); // spy on foo.func()

  expect(foo.func()).toBe('my name is foo');
  expect(spy.lastCall.thisValue).toBe(foo); // called on foo

  const bar = {
    name: 'bar',
    func: foo.func // use the func from foo
  }

  expect(bar.func()).toBe('my name is bar');
  expect(spy.lastCall.thisValue).toBe(bar); // called on bar
});