If its just for testing, Google and Microsoft each give free credits. I got $50 a month from Azure when I bought VS 2016 pro but I think they give a credit even without purchase. I got $150 from Google but runs out after a month or $150 whichever comes first. Amazon might have free credits too, or the others you mentioned.

I liked MS Azure a little better than Google. You can be up and running Ybantu 16.04 in just a few clicks. Thanks for the info on the other hosting options, I will check them out!