如何在玩笑中断言函数调用顺序

问题描述：

我正在用 jest.fn 模拟两个函数:

I am mocking two functions with with jest.fn:

let first = jest.fn();
let second = jest.fn();

如何断言 first 在 second 之前调用?

How can I assert that first called before second?

我正在寻找的是类似于 sinon's . calledBefore 断言.

What I am looking for is something like sinon's .calledBefore assertion.

更新我使用了这个简单的临时"解决方法

Update I used this simple "temporary" workaround

it( 'should run all provided function in order', () => {

  // we are using this as simple solution
  // and asked this question here https://*.com/q/46066250/2637185

  let excutionOrders = [];
  let processingFn1  = jest.fn( () => excutionOrders.push( 1 ) );
  let processingFn2  = jest.fn( () => excutionOrders.push( 2 ) );
  let processingFn3  = jest.fn( () => excutionOrders.push( 3 ) );
  let processingFn4  = jest.fn( () => excutionOrders.push( 4 ) );
  let data           = [ 1, 2, 3 ];
  processor( data, [ processingFn1, processingFn2, processingFn3, processingFn4 ] );

  expect( excutionOrders ).toEqual( [1, 2, 3, 4] );
} );

答

你可以安装 jest-community 的 jest-extended 包来代替你的解决方案，它通过 .toHaveBeenCalledBefore()，例如:

Instead of your workaround you can install jest-community's jest-extended package which provides support for this via .toHaveBeenCalledBefore(), e.g.:

it('calls mock1 before mock2', () => {
  const mock1 = jest.fn();
  const mock2 = jest.fn();

  mock1();
  mock2();
  mock1();

  expect(mock1).toHaveBeenCalledBefore(mock2);
});

注意:根据他们的文档，您需要至少 v23 的 Jest 才能使用此功能

https://github.com/jest-community/jest-extended#tohavebeencallbefore

附言- 此功能是在您发布问题几个月后添加的，因此希望这个答案仍然有帮助！

P.S. - This feature was added a few months after you posted your question, so hopefully this answer still helps!

如何在玩笑中断言函数调用顺序

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