const expect = require('expect');
const symmetricDifferenceBy = require('./symmetricDifferenceBy.js');


  test('symmetricDifferenceBy is a Function', () => {
  expect(symmetricDifferenceBy).toBeInstanceOf(Function);
});
  t.deepEqual(symmetricDifferenceBy([2.1, 1.2], [2.3, 3.4], Math.floor), [ 1.2, 3.4 ], 'Returns the symmetric difference between two arrays, after applying the provided function to each array element of both');