TypeError: Cannot read property 'prototype' of undefined + Jest + NodeJS

Question

I am using jest for unit testing in of nodeJS APIs. I have installed jest and added it to the script in package.json as well. But facing the issue:

FAIL api/test/math.test.js ● Test suite failed to run

TypeError: Cannot read property 'prototype' of undefined

 at module.exports (node_modules/request-promise-core/configure/request2.js:34:48)
 at Object.<anonymous> (node_modules/request-promise-native/lib/rp.js:15:1)
 at Object.<anonymous> (node_modules/jsdom/lib/api.js:6:17)

 Test Suites: 1 failed, 1 total
 Tests:       0 total
 Snapshots:   0 total
 Time:        0.091s
 Ran all test suites.
 npm ERR! code ELIFECYCLE
 npm ERR! errno 1
 npm ERR! [email protected] test: `jest`
 npm ERR! Exit status 1
 npm ERR!
 npm ERR! Failed at the [email protected] test script.
 npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

Below are my sample classes for the same :

math.js :

  const sum = (a, b) => a + b
  const mul = (a, b) => a * b
  const sub = (a, b) => a - b
  const div = (a, b) => a / b

  export default { sum, mul, sub, div };

math.test.js :

 const  {sum, mul, sub, div}  = require("./math")

 test("Adding 1 + 1 equals 2", () => {
   expect(sum(1, 1)).toBe(2)
 })
 test("Multiplying 1 * 1 equals 1", () => {
   expect(mul(1, 1)).toBe(1)
 })
 test("Subtracting 1 - 1 equals 0", () => {
   expect(sub(1, 1)).toBe(0)
 })
 test("Dividing 1 / 1 equals 1", () => {
   expect(div(1, 1)).toBe(1)
 })

Any suggestions are appreciated. Thanks!

Praveen Kumar Purushothaman · Accepted Answer · 2018-12-04 11:43:08Z

2

Export uses import. module.exports will give you require.

Modules & Require

You should change math.js either:

module.exports = { sum, mul, sub, div };

For the code:

const {sum, mul, sub, div} = require("./math");

Import / Export

Or you should use:

import { sum, mul, sub, div } from "./math";

For the code:

export default { sum, mul, sub, div };

It's just the right combination.

answered Dec 4, 2018 at 11:43

Praveen Kumar Purushothaman

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Comments

Elliot Lewis · Accepted Answer · 2018-12-04 11:39:38Z

1

Change your exports in math.js to be:

module.exports = { sum, mul, sub, div };

NodeJS doesn't support the ES6 import/export syntax I believe.

answered Dec 4, 2018 at 11:39

Elliot Lewis

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6 Comments

Elliot Lewis Over a year ago

Depends on the NodeJS version, no? :)

Elliot Lewis Over a year ago

stackoverflow.com/questions/48139882/… Looks like others are having a similar issue. Maybe related to the request-promise-core library?

A.P Over a year ago

How I can debug that which dependency is creating the problem. While debugging I am not seeing any dependency related error.

Praveen Kumar Purushothaman Over a year ago

@A.P Worst way, try removing one by one and check.

A.P Over a year ago

It is a sample file in one big project. It has so many dependencies that It will be difficult to remove one by one and check :(

|

Gagan Ganapathy · Accepted Answer · 2019-02-11 08:32:06Z

0

q.js :

function sum(a, b) {
  return a + b;
}

module.exports = sum;

q.test.js :

const sum = require('../src/q');

test('adds 1 + 2 to equal 3', () => {
  const result = sum(1, 3);
  expect(result).toBe(3);
});

Even this gives an error, this is exactly copied from the jest documentation! https://jestjs.io/docs/en/getting-started

answered Feb 11, 2019 at 8:32

Gagan Ganapathy

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