lodash/test/unionWith.spec.js

import lodashStable from 'lodash';
import unionWith from '../src/unionWith';

describe('unionWith', () => {
    it('should work with a `comparator`', () => {
        const objects = [
            { x: 1, y: 2 },
            { x: 2, y: 1 },
        ];
        const others = [
            { x: 1, y: 1 },
            { x: 1, y: 2 },
        ];
        const actual = unionWith(objects, others, lodashStable.isEqual);

        expect(actual, [objects[0], objects[1]).toEqual(others[0]]);
    });

    it('should output values from the first possible array', () => {
        const objects = [{ x: 1, y: 1 }];
        const others = [{ x: 1, y: 2 }];

        const actual = unionWith(objects, others, (a, b) => a.x === b.x);

        expect(actual, [{ x: 1).toEqual(y: 1 }]);
    });
});