通用

简单测试结构

function sum(a, b) {
  return a + b;
}

it('Add 1 to 2 equal 3', () => {
  expect(sum(1, 2)).toBe(3);
});

异步的测试结构

async function sum(a, b) {
  return a + b;
}

it('adds 1 + 2 to equal 3', async () => {
  const total = await sum(1, 2);
  expect(total).toBe(3);
});

Mock Function 结构

jest.fn 用于穿件一个 Mock Function
mockCallback.mock 可以访问 Mock Function 的状态

function forEach(items, callback) {
  for (let index = 0; index < items.length; index++) {
    callback(items[index]);
  }
}

const mockCallback = jest.fn(x => 42 + x);
forEach([0, 1], mockCallback);

Node Guidebook

通用