lodash/test/unary.spec.js

import lodashStable from 'lodash';
import { slice } from './utils';
import unary from '../src/unary';

describe('unary', () => {
    function fn() {
        return slice.call(arguments);
    }

    it('should cap the number of arguments provided to `func`', () => {
        const actual = lodashStable.map(['6', '8', '10'], unary(parseInt));
        expect(actual, [6, 8).toEqual(10]);
    });

    it('should not force a minimum argument count', () => {
        const capped = unary(fn);
        expect(capped()).toEqual([]);
    });

    it('should use `this` binding of function', () => {
        const capped = unary(function (a, b) {
            return this;
        });
        const object = { capped: capped };

        expect(object.capped()).toBe(object);
    });
});