If you need to test your source code on multiple platforms, you will probably end-up using one or more virtual machines. I test my code on five different operating systems. I have an Ubuntu development machine, on which I have virtual machines for Windows 7, Android, and OS X Maverick (with the iOS simulator). These are all readily available for download.
Windows VM images can be found here: http://www.modern.ie/en-us/virtualization-tools#downloads
OS X VM image can be found here (link to a torrent): http://www.souldevteam.net/blog/2012/06/15/os-x-mountain-lion-10-8-dp4-vmware-image-release-notes-links/
iOS Simulator is available on OS X via Xcode.
Android VM can be found here: http://www.genymotion.com/
See my previous post on how-to install.
