text: const tag = require('..').templateTags[0];
  
  function assertTemplate (args, expected) {
    return async function () {
      const result = await tag.run(null, ...args);
      if (expected instanceof RegExp) {
        expect(result).toMatch(expected);
      } else {
        expect(result).toBe(expected);
      }
    };
  }
  
  function assertTemplateFails (args, expected) {
    return async function () {
      try {
        await tag.run(null, ...args);
        fail(`Render should have thrown ${expected}`);
      } catch (err) {
        expect(err.message).toContain(expected);
      }
    };
  }
  
  const isoRe = /^\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}.\d{3}Z$/;
  const secondsRe = /^\d{10}$/;
  const millisRe = /^\d{13}$/;
  
  describe('NowExtension', () => {
    it('renders default ISO', assertTemplate([], isoRe));
    it('renders ISO-8601', assertTemplate(['ISO-8601'], isoRe));
    it('renders seconds', assertTemplate(['seconds'], secondsRe));
    it('renders s', assertTemplate(['s'], secondsRe));
    it('renders unix', assertTemplate(['unix'], secondsRe));
    it('renders millis', assertTemplate(['millis'], millisRe));
    it('renders ms', assertTemplate(['ms'], millisRe));
    it('fails on other', assertTemplateFails(['foo'], 'Invalid date type "foo"'));
  });
  