spec.js

const dd = require('.');

describe('double-digit', () => {
	[
		[ 0, '00' ],
		[ 1, '01' ],
		[ 9.9, '09.9' ],
		[ 0.001, '00.001' ],
		[ 1e3, '1000' ],
	].forEach(([ n, r ]) => {
		it(
			`Should convert ${n} to ${r}`,
			() => expect(dd(n)).to.equal(r),
		);
		it(
			`${r} should represent ${n}`,
			() => expect(Number(r)).to.equal(n),
		);
	});
	[
		[ '2', '02' ],
		[ '2.0001', '02.0001' ],
		[ '12', '12' ],
		[ 'Hello', 'Hello' ],
		[ undefined, undefined ],
		[ false, false ],
		[ null, null ],
		[ Infinity, Infinity ],
		[ -Infinity, -Infinity ],
	].forEach(([ n, r ]) => {
		it(
			`Should convert ${n} to ${r}`,
			() => expect(dd(n)).to.equal(r),
		);
	});
	it('Should not convert NaN', () => {
		const result = dd(NaN);
		expect(result).to.be.a('number');
		expect(Number.isNaN(result)).to.be.true;
	});
});