CODEWITHSUNDEEP
reactjsunit-testingjestjsenzyme
EMC
EMC

Reputation: 1930

How do you mock a react component with Jest that has props?

There has got to be a simple way to do this, but I can't find documented syntax anywhere. I have a React component with a prop that I'd like to mock in Jest like this:

jest.mock('./common/MultiSelect', 'MultiSelect');

That works, except that I end up with a React warning cluttering my test results:

Warning: Unknown prop options on tag. Remove this prop from the element.

The component I'm mocking does have an options prop, and I really don't care how it's rendered, so how can I mock it in such a way it will not throw the warning? I've tried using React.createElement in the mock, and returning an array with element name and props arguments to no end.

The component I want to mock is used like this:

<MultiSelect
options={['option 1', 'option 2']}
/>

Upvotes: 16

Views: 33834

Answers (3)

HydraHatRack
HydraHatRack

Reputation: 1300

I find the following mock pattern useful in cases where you want to see the component name and props being provided in your Jest snapshots:

jest.mock('./common/MultiSelect', () => (props) => <mock-MultiSelect {...props} />);

Upvotes: 9

EMC
EMC

Reputation: 1930

After playing around with it, I realized I had the syntax wrong for my returned component. Mocking it like this works:

jest.mock('../../../../../common/components/MultiSelect/MultiSelect', () => () => <div />);

Mocking it like this doesn't (this is what I was doing):

jest.mock('../../../../../common/components/MultiSelect/MultiSelect', () => <div />);

The warning even told me the issue, but I misinterpreted it:

Warning: React.createElement: type is invalid -- expected a string (for built-in components) or a class/function (for composite components) but got: object. Check the render method of Termination.

Upvotes: 3

Ben McCormick
Ben McCormick

Reputation: 25728

You're mocking the component with a string as the second argument. That's unusual, as the jest.mock function expects a function as a second argument. The string may work for your test (depending on how it is rendered) but it's undefined behavior in Jest's documentation and is probably what is causing your problem. Instead pass a function that returns a component. Here's one that passes a simple functional component that just passes the name back:

jest.mock('./common/MultiSelect', () => () =><span>MultiSelect</span>);

Upvotes: 17

Related Questions