How can I test my web app against China's Great Firewall?

I need to ensure my web-based application (desktop browser and cordova app) works correctly when the user is located in mainland China and subject to filtering by the Great Firewall (GF). The app loads a number of 3rd party javascript files, including google maps, google places, google analytics, and communicates with various servers via AJAX. In the future there will surely be other domains that the app needs to communicate with, so this is not just a "how do I make it work with Google Maps" question.

How can I test this scenario? It's not as simple as just blocking all network access, or even certain domains. Sometimes the GF blocks urls within a domain. The exact rules it uses are unclear will surely change over time.

It seems like the best solution is some sort of VPN with endpoint(s) in China that purposely route traffic through areas that are filtered by the GF. I have yet to find such a service.