lodash/test/isNumber.test.js

import assert from 'assert';
import lodashStable from 'lodash';
import { falsey, args, slice, symbol, realm } from './utils.js';
import isNumber from '../isNumber.js';

describe('isNumber', function() {
  it('should return `true` for numbers', function() {
    assert.strictEqual(isNumber(0), true);
    assert.strictEqual(isNumber(Object(0)), true);
    assert.strictEqual(isNumber(NaN), true);
  });

  it('should return `false` for non-numbers', function() {
    var expected = lodashStable.map(falsey, function(value) {
      return typeof value === 'number';
    });

    var actual = lodashStable.map(falsey, function(value, index) {
      return index ? isNumber(value) : isNumber();
    });

    assert.deepStrictEqual(actual, expected);

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

  it('should work with numbers from another realm', function() {
    if (realm.number) {
      assert.strictEqual(isNumber(realm.number), true);
    }
  });
});