To test my applications in the cloud I often use digital ocean (https://cloud.digitalocean.com).
After you have registered yourself at digital ocean (you need a credit card for that) you will be able to create a new ‘droplet’ (virtual machine).
You can choose the size (memory/cpu) of the droplet and choose which operating system you would like to use.
I often choose the 1GB/1CPU version and install ubuntu on that system.
When pressing ‘create droplet’ the system is build and started, This takes about two minutes, so that is really fast.
In the meantime the root password and the public ip address of that system is sent to you by email and when the droplet is started, you can ssh to the system and start using it.
I oftern just use it for testing and need it only for a single day or so (I normally work on a virtual machine on my laptop),
After you are finished with testing you can just destroy the droplet so you only have to pay for the few hours that you worked on it.
For the system configuration that I normally choose, I only need to pay 10 cent for 8 hours of renting it!