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reactjsjestjscreate-react-app

How to test with jest

I am learning to test with the create-react-app built-in testing tools. I have successfully tested some dumb components and fetch calls but when I added a simple function test something goes wrong. I have searched for answers and I cannot tell if it is a bug or if I am doing it wrong. This is the function I am testing.

 export default async function (trips, users) {
  let arry = []

  trips.forEach(trip => {
    if (trip.get('distance') !== '0.0' || trip.get('distance') !== 0.0) {
      users.forEach(user => {
        let hours = 0
        if (trip.get('userId') === user.get('id')) {
          if (trip.get('duration')) {
            hours += toSeconds(trip.get('duration'))
            hours = toHHMMSS(hours)
            hours = roundTime(hours)

            const obj = {
              hours: parseInt(hours), // eslint-disable-line
              fullName: user.get('fullName'),
              id: user.get('id')
            }
            arry.push(obj)
          }
        }
      })
    }
  })

  return arry
}

Here is the test

 test('user hours for summary', () => {
  let tripsData = testData.TRIPS_DATA
  let usersData = testData.USERS_DATA
  tripsData = Immutable.fromJS(tripsData)
  usersData = Immutable.fromJS(usersData)
  return userHours(tripsData, usersData).then(res => {
    expect(res).toEqual(testData.USER_HOURS_RESULT)
  })
})

Here is screenshot of console Screenshot

I am also using

"custom-react-scripts": "^0.2.1"

instead of the default react-scripts. I thought that could be the problem but when I switched back it was throwing the same error.

"test": "react-scripts test --coverage --env=jsdom"

Solution

  • Based on this and this, it seems that this could be caused by a bug in create-react-app. Try running the test without coverage mode to see if it works.

    If it still doesn't work then the presence of a bug is much less likely. Maybe append a .catch() to the promise that you return to see if there's an error in your function that's been getting by undetected one way or another.