Unit test for prime finder actor.

TestPrimeFinderActor.js

describe('PrimeFinderActor', () => {
  it('should correctly find next prime', () => {
    const pf = new PrimeFinderActor();

    expect(pf.nextPrime(1)).to.be.equal(2);
    expect(pf.nextPrime(2)).to.be.equal(3);
    expect(pf.nextPrime(3)).to.be.equal(5);
    expect(pf.nextPrime(30)).to.be.equal(31);
  });

  it('should only accept positive numbers', () => {
    const pf = new PrimeFinderActor();

    expect(() => pf.nextPrime(0)).to.throw();
    expect(() => pf.nextPrime(-1)).to.throw();
  });
});