How to test and debug website on older version of Safari
Very easy.

Get a copy of Parallels or VMware Fusion. Set up a virtual machine and install Mavericks on it. You will then have all the benefits of running Safari 7 in the original environment without having to dust the hardware.

I have Fusion, and virtual machines back to 10.5 Leopard. Also have Windows back to W98, and DOS 6 just for Duke Nukem in all it's 8-bit glory. modern.ie has free downloads of ready-to-go virtual machines for all versions of MSIE.

Other things you should have:


lots of disk space. Like > 250GB
lots of memory. VMs don't share memory, they need their own. I have 24GB.
a big monitor, or a second monitor.