Merge pull request #146 from JCook21/issue134

Fix for issue134

lib/homesick/cli.rb

@@ -25,10 +25,13 @@ module Homesick
         exit(1)
       end
       # Hack in support for diffing symlinks
+      # Also adds support for checking if destination or content is a directory
       shell_metaclass = class << shell; self; end
       shell_metaclass.send(:define_method, :show_diff) do |destination, content|
         destination = Pathname.new(destination)
-        return super unless destination.symlink?
+        content = Pathname.new(content)
+        return 'Unable to create diff: destination or content is a directory' if destination.directory? || content.directory?
+        return super(destination, content) unless destination.symlink?
         say "- #{destination.readlink}", :red, true
         say "+ #{content.expand_path}", :green, true
       end