lodash/test/takeRightWhile.spec.ts

import assert from 'node:assert';
import lodashStable from 'lodash';
import { slice, LARGE_ARRAY_SIZE } from './utils';
import takeRightWhile from '../src/takeRightWhile';

describe('takeRightWhile', () => {
    const array = [1, 2, 3, 4];

    const objects = [
        { a: 0, b: 0 },
        { a: 1, b: 1 },
        { a: 2, b: 2 },
    ];

    it('should take elements while `predicate` returns truthy', () => {
        const actual = takeRightWhile(array, (n) => n > 2);

        assert.deepStrictEqual(actual, [3, 4]);
    });

    it('should provide correct `predicate` arguments', () => {
        let args;

        takeRightWhile(array, function () {
            args = slice.call(arguments);
        });

        assert.deepStrictEqual(args, [4, 3, array]);
    });

    it('should work with `_.matches` shorthands', () => {
        assert.deepStrictEqual(takeRightWhile(objects, { b: 2 }), objects.slice(2));
    });

    it('should work with `_.matchesProperty` shorthands', () => {
        assert.deepStrictEqual(takeRightWhile(objects, ['b', 2]), objects.slice(2));
    });

    it('should work with `_.property` shorthands', () => {
        assert.deepStrictEqual(takeRightWhile(objects, 'b'), objects.slice(1));
    });

    it('should work in a lazy sequence', () => {
        const array = lodashStable.range(LARGE_ARRAY_SIZE),
            predicate = function (n) {
                return n > 2;
            },
            expected = takeRightWhile(array, predicate),
            wrapped = _(array).takeRightWhile(predicate);

        assert.deepEqual(wrapped.value(), expected);
        assert.deepEqual(wrapped.reverse().value(), expected.slice().reverse());
        assert.strictEqual(wrapped.last(), _.last(expected));
    });

    it('should provide correct `predicate` arguments in a lazy sequence', () => {
        let args,
            array = lodashStable.range(LARGE_ARRAY_SIZE + 1);

        const expected = [
            square(LARGE_ARRAY_SIZE),
            LARGE_ARRAY_SIZE - 1,
            lodashStable.map(array.slice(1), square),
        ];

        _(array)
            .slice(1)
            .takeRightWhile(function (value, index, array) {
                args = slice.call(arguments);
            })
            .value();

        assert.deepEqual(args, [LARGE_ARRAY_SIZE, LARGE_ARRAY_SIZE - 1, array.slice(1)]);

        _(array)
            .slice(1)
            .map(square)
            .takeRightWhile(function (value, index, array) {
                args = slice.call(arguments);
            })
            .value();

        assert.deepEqual(args, expected);

        _(array)
            .slice(1)
            .map(square)
            .takeRightWhile(function (value, index) {
                args = slice.call(arguments);
            })
            .value();

        assert.deepEqual(args, expected);

        _(array)
            .slice(1)
            .map(square)
            .takeRightWhile(function (index) {
                args = slice.call(arguments);
            })
            .value();

        assert.deepEqual(args, [square(LARGE_ARRAY_SIZE)]);

        _(array)
            .slice(1)
            .map(square)
            .takeRightWhile(function () {
                args = slice.call(arguments);
            })
            .value();

        assert.deepEqual(args, expected);
    });
});