Fakeout your environment variables, maybe for your tests.
test('fakeout $HOME', (assert) => {
assert.equal(process.env.HOME, '/Users/rclark', 'yep, that is correct');
const env = new FakeEnv({
HOME: '/tricked/you'
});
assert.equal(process.env.HOME, '/tricked/you', 'ooooh its been mocked!');
env.restore();
assert.equal(process.env.HOME, '/Users/rclark', 'restored to normal');
assert.end();
});