cross-ci/test/vars/YEAR.spec.js

`cross-ci` standardizes environment variables for CI. For example, your can simply use `BUILD_BRANCH` variable in all CI runners instead of `CIRCLE_BRANCH` in CircleCI or `TRAVIS_PULL_REQUEST_BRANCH` in Travis.

const createVars = require('../../lib/createVars');

describe('YEAR', () => {
    test('returns correct year', async () => {
        const vars = await createVars({});

        expect(vars.YEAR).toBe(String((new Date()).getFullYear()));
    });
});