How can I test the auto renewable scenarios that are described here with SwiftyStoreKit?

### Platform

- [x] iOS
- [ ] macOS
- [ ] tvOS

### In app purchase type

- [ ] Consumable
- [ ] Non-consumable
- [x] Auto-Renewable Subscription
- [ ] Non-Renewing Subscription

### Environment

- [x] Sandbox
- [ ] Production

### Version
ℹ Please replace this with the version of SwiftyStoreKit you're using.

### Related issues
ℹ Please replace this with references to similar issues (either open or already closed).

## Report

### Issue summary
ℹ Please replace this with an explanation of the issue, including reproduction steps.

### What did you expect to happen
ℹ Please replace this with what you expected to happen.

According to:
http://davidbarnard.com/post/164337147440/testing-auto-renewable-subscriptions-on-ios

The subscription will automatically renew 6 times per account per 8 hour window, then the subscription will automatically expire at the end of each subscription period.

### What happened instead
ℹ Please replace this with what happened instead.

Specifically what I found is that the subscription does not automatically renew. This means that say I subscribe for 1 month, after 5 minutes, SwiftyStoreKit.verifySubscription returns .expired immediately. Shouldn't it still return .purchased for 6 times before it expired?

I have also tested it for 1 year duration, and it is the same behavior. Never auto-renewal. I will like to get this behavior so that I can update my renewal date in the UI. Is that possible?