Jest: Error: Your test suite must contain at least one test

I am implementing jest to test my React app and have set up a simple test on a utility function I have, but I am getting the error:

Error: Your test suite must contain at least one test.

Have checked my implementation, and I think all is correct - could someone take a look got me?

The file structure for the test and the function is as follows

- __tests__
  -- sumObjectValues-test.js
- utils
  -- sumObjectValues.js

sumObjectValues.js is as follows:

const sumObjectValues = (obj, identifier) => {
    return obj
        .map((el) => { return el[identifier]; })
        .reduce((prev, next) => { return prev += next; }, 0);
}

export default sumObjectValues;

And sumObjectValues-test.js:

   const obj = [
    {
        "id": 0,
        "item": "Tesla Model S",
        "amount": 85000
    },
    {
        "id": 1,
        "item": "iPhone 6S",
        "amount": 600
    },
    {
        "id": 2,
        "item": "MacBook Pro",
        "amount": 1700
    }
];

const identifier = "amount";


jest.unmock('../client/utils/sumObjectValues'); // unmock to use the actual implementation of sumObjectValues

describe('sumObjectValues', () => {
    if('takes an array of objects, each with amount values, & sums the values', () => {
        const sumObjectValues = require('../client/utils/sumObjectValues');
        expect(sumObjectValues(obj, identifier)).toBe(87300);
    });
});

Then I have "test": "jest" in my package.json scripts, but get the following error:

FAIL tests/sumObjectValues-test.js (0s) ● Runtime Error - Error: Your test suite must contain at least one test. at onTestResult (node_modules/jest-cli/build/TestRunner.js:143:18) 1 test suite failed, 0 tests passed (0 total in 1 test suite, run time 13.17s) npm ERR! Test failed. See above for more details.

Thanks all :)