how to write test cases for react hooks jest enzyme code example
Example: react enzyme hooks test
import React from 'react'
import FetchData from './FetchData'
const fetchUsers = () =>
fetch('https://jsonplaceholder.typicode.com/users').then((res) => res.json())
function App() {
return (
<>
<FetchData fetchUsers={fetchUsers} />
</>
)
}
export default App
import React, { useState } from 'react'
function fetchData({ fetchUsers }) {
const [state, setState] = useState([])
React.useEffect(() => {
fetchUsers().then(setState)
}, [])
return (
<>
{state &&
state.map((val, id) => (
<ul key={id}>
<li>{val.name}</li>
</ul>
))}
</>
)
}
export default fetchData
import React from 'react'
import { shallow } from 'enzyme'
import FetchData from '../FetchData'
describe('Fetch All Data Hooks', () => {
let props
let wrapper
let useEffect
const users = [
{ id: 1, name: 'jamal' },
{ id: 2, name: 'karyo' },
{ id: 3, name: 'mirdad' }
]
beforeEach(() => {
useEffect = jest.spyOn(React, 'useEffect').mockImplementationOnce((f) => f())
props = { fetchUsers: jest.fn().mockResolvedValue(users) }
wrapper = shallow(<FetchData {...props} />)
})
afterAll(() => {
jest.clearAllMocks()
})
it('result all users', () => {
expect(useEffect).toHaveBeenCalled()
expect(props.fetchUsers).toHaveBeenCalled()
expect(props.fetchUsers).toHaveBeenCalledTimes(1)
expect(jest.isMockFunction(props.fetchUsers)).toBeTruthy()
})
it('find render all users exits count', () => {
expect(wrapper.find('ul > li')).toHaveLength(3)
expect(
wrapper.containsAllMatchingElements([
<ul>
<li>jamal</li>
</ul>,
<ul>
<li>karyo</li>
</ul>,
<ul>
<li>mirdad</li>
</ul>
])
).toBeTruthy()
})
})