integer/test/11.from-number.js

Native 64-bit integers with overflow protection.

'use strict';
const expect = require('chai').expect;
const Integer = require('../.');
const fromNumber = Integer.fromNumber;

function equal(a, b) {
	expect(a).to.be.an.instanceof(Integer);
	expect(a.toNumber()).to.equal(b);
}

describe('Integer.fromNumber()', function () {
	it('should work with a number argument', function () {
		equal(fromNumber(0), 0);
		equal(fromNumber(123), 123);
		equal(fromNumber(-123), -123);
		equal(fromNumber(-1, 500), -1);
		equal(fromNumber(Number.MAX_SAFE_INTEGER), Number.MAX_SAFE_INTEGER);
		equal(fromNumber(Number.MIN_SAFE_INTEGER), Number.MIN_SAFE_INTEGER);
	});
	it('should throw when the argument is an unaccepted type', function () {
		expect(() => fromNumber()).to.throw(TypeError);
		expect(() => fromNumber(undefined)).to.throw(TypeError);
		expect(() => fromNumber(null)).to.throw(TypeError);
		expect(() => fromNumber([])).to.throw(TypeError);
		expect(() => fromNumber(new Number(123))).to.throw(TypeError);
		expect(() => fromNumber('123')).to.throw(TypeError);
		expect(() => fromNumber(Integer(123))).to.throw(TypeError);
	});
	it('should throw when the argument is a non-integer number', function () {
		expect(() => fromNumber(0.1)).to.throw(TypeError);
		expect(() => fromNumber(-0.1)).to.throw(TypeError);
		expect(() => fromNumber(Infinity)).to.throw(TypeError);
		expect(() => fromNumber(-Infinity)).to.throw(TypeError);
		expect(() => fromNumber(NaN)).to.throw(TypeError);
		expect(() => fromNumber(Number.EPSILON / 2)).to.throw(TypeError);
	});
	it('should throw when the argument is an unsafe number', function () {
		expect(() => fromNumber(Number.MAX_SAFE_INTEGER + 1)).to.throw(RangeError);
		expect(() => fromNumber(Number.MIN_SAFE_INTEGER - 1)).to.throw(RangeError);
	});
	it('should accept default values as an alternative to throwing exceptions', function () {
		expect(() => fromNumber(undefined, 0)).to.throw(TypeError);
		expect(() => fromNumber('123', 0)).to.throw(TypeError);
		expect(() => fromNumber(Integer(123), 0)).to.throw(TypeError);
		equal(fromNumber(0.1, 123), 123);
		equal(fromNumber(-0.1, Integer(456)), 456);
		equal(fromNumber(Infinity, -2), -2);
		equal(fromNumber(Number.MAX_SAFE_INTEGER + 1, Integer(555)), 555);
		expect(fromNumber(Number.MIN_SAFE_INTEGER - 1, Integer.ONE)).to.equal(Integer.ONE);
	});
	it('should throw when the default value is not valid', function () {
		expect(() => fromNumber(Number.MAX_SAFE_INTEGER + 1, '123')).to.throw(TypeError);
		expect(() => fromNumber(Number.MAX_SAFE_INTEGER + 1, new Number(123))).to.throw(TypeError);
		expect(() => fromNumber(Number.MAX_SAFE_INTEGER + 1, 2.2)).to.throw(TypeError);
		expect(() => fromNumber(Number.MAX_SAFE_INTEGER + 1, Infinity)).to.throw(TypeError);
		expect(() => fromNumber(Number.MAX_SAFE_INTEGER + 1, Number.MAX_SAFE_INTEGER + 1)).to.throw(TypeError);
	});
});