index.test.js

import each from 'jest-each';

import matcher from './';

expect.extend(matcher);

describe('.toBeValidDate', () => {
  test('passes when given a valid date', () => {
    expect(new Date()).toBeValidDate();
  });

  test('fails when given an invalid date', () => {
    expect(() => expect(new Date('01/90/2017')).toBeValidDate()).toThrowErrorMatchingSnapshot();
  });

  test('fails when not given non-date values', () => {
    expect(() => expect(1).toBeValidDate()).toThrowErrorMatchingSnapshot();
  });
});

describe('.not.toBeValidDate', () => {
  each([
    [new Date('01/90/2018')],
    [new Date('32/01/2018')],
    [false],
    [true],
    [0],
    [''],
    [{}],
    [() => {}],
    [undefined],
    [null],
    [NaN]
  ]).test('passes when not given a date: %s', given => {
    expect(given).not.toBeValidDate();
  });

  test('fails when not given a valid date value', () => {
    expect(() => expect(new Date('01/01/2018')).not.toBeValidDate()).toThrowErrorMatchingSnapshot();
  });
});