【Bun中文文档-Test runner】Mocks

你可以使用 mock 函数来创建模拟函数。

import { test, expect, mock } from "bun:test";
const random = mock(() => Math.random());

test("random", async () => {
  const val = random();
  expect(val).toBeGreaterThan(0);
  expect(random).toHaveBeenCalled();
  expect(random).toHaveBeenCalledTimes(1);
});

或者，你也可以使用 jest.fn() 函数，就像在 Jest 中一样。它的行为是相同的。

import { test, expect, jest } from "bun:test";
const random = jest.fn(() => Math.random());

test("random", async () => {
  const val = random();
  expect(val).toBeGreaterThan(0);
  expect(random).toHaveBeenCalled();
  expect(random).toHaveBeenCalledTimes(1);
});

mock() 的结果是一个经过装饰的新函数，具有一些额外的属性。

import { mock } from "bun:test";
const random = mock((multiplier: number) => multiplier * Math.random());

random(2);
random(10);

random.mock.calls;
// [[ 2 ], [ 10 ]]

random.mock.results;
//  [
//    { type: "return", value: 0.6533907460954099 },
//    { type: "return", value: 0.6452713933037312 }
//  ]

以下属性和方法在模拟函数上已经实现了。

• mockFn.getMockName()
• mockFn.mock.calls
• mockFn.mock.results
• mockFn.mock.instances
• mockFn.mock.contexts
• mockFn.mock.lastCall
• mockFn.mockClear()
• mockFn.mockReset()
• mockFn.mockRestore()
• mockFn.mockImplementation(fn)
• mockFn.mockImplementationOnce(fn)
• mockFn.mockName(name)
• mockFn.mockReturnThis()
• mockFn.mockReturnValue(value)
• mockFn.mockReturnValueOnce(value)
• mockFn.mockResolvedValue(value)
• mockFn.mockResolvedValueOnce(value)
• mockFn.mockRejectedValue(value)
• mockFn.mockRejectedValueOnce(value)
• mockFn.withImplementation(fn, callback)

.spyOn()

你可以在不替换函数的情况下跟踪对函数的调用。使用 spyOn() 来创建一个 spy，这些 spy 可以传递给 .toHaveBeenCalled() 和 .toHaveBeenCalledTimes()。

import { test, expect, spyOn } from "bun:test";

const ringo = {
  name: "Ringo",
  sayHi() {
    console.log(`Hello I'm ${this.name}`);
  },
};

const spy = spyOn(ringo, "sayHi");

test("spyon", () => {
  expect(spy).toHaveBeenCalledTimes(0);
  ringo.sayHi();
  expect(spy).toHaveBeenCalledTimes(1);
});