serge1peshcoff serge1peshcoff - 1 year ago 270
Javascript Question

Jest - expect(...).toContainEqual is not a function

I am using Jest to test my Node.JS application and when I run my tests, some built-in functions don't work, it seems like they are not defined. For instance,


Here is example of my code:

it('should delete DB entry', () => query(url, queryString)
.then(res => res.json()
.then(() => db.collection('exercises').find({}).toArray()))
.then(res => expect(res).toContainEqual(originalExercise)))

And the error I'm getting:

TypeError: expect(...).toContainEqual is not a function

But the other functions (like
) work fine though.

I am using Jest v15.1.1 (according to
jest -v

How can I deal with it?

Answer Source

toContainEqual and toBeInstanceOf is NOT included in v15.1.1 yet. To use these 2 matchers, you need to install jest@15.2.0-alpha.c681f819, or just wait for the next release.

According to the Jest code history, toContainEqual was merged on Sep. 20th ( and toBeInstanceOf was merged on Sep. 7th ( However, v15.1.1 was released on Sep. 2th.

It seems the API page of Jest should be changed, so that un-released API won't be included.

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