lodash/test/isNull.spec.ts

import assert from 'node:assert';
import lodashStable from 'lodash';
import { falsey, args, slice, symbol, realm } from './utils';
import isNull from '../src/isNull';

describe('isNull', () => {
    it('should return `true` for `null` values', () => {
        assert.strictEqual(isNull(null), true);
    });

    it('should return `false` for non `null` values', () => {
        const expected = lodashStable.map(falsey, (value) => value === null);

        const actual = lodashStable.map(falsey, (value, index) =>
            index ? isNull(value) : isNull(),
        );

        assert.deepStrictEqual(actual, expected);

        assert.strictEqual(isNull(args), false);
        assert.strictEqual(isNull([1, 2, 3]), false);
        assert.strictEqual(isNull(true), false);
        assert.strictEqual(isNull(new Date()), false);
        assert.strictEqual(isNull(new Error()), false);
        assert.strictEqual(isNull(slice), false);
        assert.strictEqual(isNull({ a: 1 }), false);
        assert.strictEqual(isNull(1), false);
        assert.strictEqual(isNull(/x/), false);
        assert.strictEqual(isNull('a'), false);
        assert.strictEqual(isNull(symbol), false);
    });

    it('should work with nulls from another realm', () => {
        if (realm.object) {
            assert.strictEqual(isNull(realm.null), true);
        }
    });
});