How to get 'diff' on Windows TravisCI machines?
When git is installed it usually doesn't add the diff executable to the path because it would conflict with other versions of diff native to Windows, for example, the Compare-Object alias in PowerShell.


You can usually get around this by adding C:\Program Files\Git\usr\ to the path which contains all of the UNIX ports of functionality such diff, grep, awk, sed.  You do have to be careful as some commands are used more commonly on Windows than others, the most common one is find.
A second option would be to fully qualify the call to diff by appending C:\Program Files\Git\usr\bin.