CODEWITHSUNDEEP
jestjs
user776686
user776686

Reputation: 8655

Jest assertion - object containing a key

In Jest I need to test an expected value which can be either null or an object

{
  main: {
    prop1: 'abc',
    prop2: '123',
  }
}

but if it is an object, then I don't really care what main contains, I don't care about prop1 or prop2. I only need to assert that the object contains a key named main.

Jest reference mentions objectContaining, but it would still require that I specify at least one of the props, thus making my code unnecessarily verbose.

Is there any swift way to achieve an assertion that could be named objectContainingKey, like:

expect(something).toEqual(expect.objectContainingKey('main'))

Upvotes: 9

Views: 13953

Answers (3)

Mark Fox
Mark Fox

Reputation: 8924

Assuming

const something = {
  main: {
    prop1: 'abc',
    prop2: '123',
  }
}

Then you can use objectContaining and any to check that something is an object containing a key main which contains an object

expect(something).toEqual(
  expect.objectContaining({
    main: expect.any(Object),
  });
);

Upvotes: 8

Lucio Mollinedo
Lucio Mollinedo

Reputation: 2424

The docs have something more suitable and more readable than the accepted answer:

expect(obj.main).toBeDefined();

Upvotes: 9

Eka putra
Eka putra

Reputation: 759

or you can do it in a way that is a little tricky

const something = { main: { prop1: 'abc', prop2: '123' } }

expect(Object.keys(something).toString()).toBe('main')

and

expect(Object.keys(something.main).toString()).toBe('prop1')
expect(Object.keys(something.main).toString()).toBe('prop2')

or

expect(Object.keys(something.main))
  .toEqual(expect.arrayContaining(['prop1', 'prop2']))

Upvotes: 6

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