测试是否使用参数调用函数

Question

所以...我只是想检查我的 sut 是否以这种方式使用依赖项，它是否会被调用至少 N 次并带有适当的参数。如果没有查找.mock.calls 条目并找到合适的条目的肮脏技巧，我无法找到一种方法。理想情况下，我希望代码看起来像这样：

it('...', () => {
  const dependency = jest.fn();
  const sut = createSut(dependency);

  sut();

  // that is of course wrong because of syntax but it shows what I want:
  expect(dependency).toBeCalledWith({ some: 'arguments' }).times(5);

  // this doesn't work - if at least one call was made it will always pass
  for (let i = 0; i < 5: ++i)
    expect(dependency).toBeCalledWith({ some: 'arguments' });

  // this doesn't work either, 'cause at least one proper call will make tests pass
  expect(dependency.mock.calls.length).toBeGreaterThanOrEqual(5);
  expect(dependency).toBeCalledWith({ some: 'arguments' });
});

是否可以在不使用其他库（如 chai）的情况下在 jest 中获取我想要的内容？

Answer 1

您应该能够使用jests's matchers 编写测试。

// Called just 5 times
expect(dependency).toHaveBeenCalledTimes(5);

// Called with same argument
[1,2,3,4,5].forEach(time => {
  expect(dependency).toHaveBeenNthCalledWith(time, {
    some: 'arguments',
  });
});

// Called with different arguments
const expectedArguments = [
  {some: 'arguments'},
  null,
  14,
  {some:'arguments'},
  {some:'arguments'},
];

expectedArguments.forEach((argument, index) => {
  const callNumber = index + 1;
  expect(dependency).toHaveBeenNthCalledWith(callNumber, argument);
});