Question: So I moved some X programs down to the mac, and I'm getting

```
Error: XTEST extension unavailable on '(null)'.

```

from xdotool.

* Does OS X X11 come with XTEST?
* If not, is there a way to add it?

Answer: 
I had to do the following two commands to get this to work on Mountain Lion (from [here](http://xquartz.macosforge.org/trac/ticket/526)):

```
defaults write org.x.X11 enable_test_extensions -boolean true
defaults write org.macosforge.xquartz.X11 enable_test_extensions -boolean true

```
For XQuartz,

```
defaults write org.macosforge.xquartz.X11 enable_test_extensions -bool yes

```

See [this link](https://xquartz.macosforge.org/trac/ticket/414).