javascript - Jest : expect object not to have property

Question

我想编写一个断言给定对象不具有某些属性的测试。

假设我有一个函数

function removeFooAndBar(input) {
  delete input.foo;
  delete input.bar;
  return input;
}

现在我要写一个测试:

describe('removeFooAndBar', () => {
  it('removes properties `foo` and `bar`', () => {
    const data = {
      foo: 'Foo',
      bar: 'Bar',
      baz: 'Baz',
    };
    expect(removeFooAndBar(data))
      .toEqual(expect.objectContaining({
        baz: 'Baz', // what's left
        foo: expect.not.exists() // pseudo
        bar: undefined // this doesn't work, and not what I want
      }));
  });
});

断言的正确方法是什么？

Answer 1

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您可以使用 expect.not.objectContaining() .这种方法工作正常，但有一个不幸的边缘情况:它在属性存在但 undefined 或 null 时匹配。要解决此问题，您可以明确添加要包含在检查中的那些值。你需要 jest-extended toBeOneOf() 的包裹匹配器。

expect({foo: undefined}).toEqual(expect.not.objectContaining(
    {foo: expect.toBeOneOf([expect.anything(), undefined, null])}
));

嵌套 Prop 失败的示例:

const reallyAnything = expect.toBeOneOf([expect.anything(), undefined, null]);

expect({foo: undefined, bar: {baz: undefined}}).toEqual(
    expect.not.objectContaining(
        {
            foo: reallyAnything,
            bar: {baz: reallyAnything},
        }
    )
);

---

原始答案

我要做的是显式检查对象是否具有名为 bar 或 foo 的属性。

delete data.foo;
delete data.bar;
delete data.nested.property; 

expect(data).not.toHaveProperty('bar');
expect(data).not.toHaveProperty('foo');
expect(data.nested).not.toHaveProperty('property');
// or
expect(data).not.toHaveProperty('nested.property');

或者通过遍历将被删除的属性来减少重复。

const toBeRemoved = ['foo', 'bar'];

toBeRemoved.forEach((prop) => {
    delete data[prop];
    expect(data).not.toHaveProperty(prop);
});

但是，循环方法对于可能的嵌套对象来说并不是太好。 我相信你要找的是expect.not.objectContaining()

expect(data).toEqual(expect.not.objectContaining({foo: 'Foo', bar: 'Bar'}));

expect.not.objectContaining(object) matches any received object that does not recursively match the expected properties. That is, the expected object is not a subset of the received object. Therefore, it matches a received object which contains properties that are not in the expected object. - Jest Documentation