Improve installer

Don't choke on non-directory or non-git directories: continue on and
print a warning.

This is useful so you can run `overcommit *` in a directory and just
install to all of the matching targets that are Git repositories.

Change-Id: Ie5b617f7753a617ac6405464aa3901b49b7fffd9
Reviewed-on: https://gerrit.causes.com/22813
Tested-by: jenkins <jenkins@causes.com>
Reviewed-by: Joe Lencioni <joe.lencioni@causes.com>

Author: Aiden Scandella

changelog.md

@@ -1,5 +1,6 @@
 0.1.1
 
+* Make installer more robust
 * Improve readme documentation
 * Add template listing (-l) to CLI
 * Add rspec and super-basic spec coverage

lib/overcommit.rb

@@ -1,5 +1,6 @@
 require 'overcommit/configuration'
 require 'overcommit/console_methods'
+require 'overcommit/errors'
 require 'overcommit/git_hook'
 require 'overcommit/hook_specific_check'
 require 'overcommit/installer'

lib/overcommit/cli.rb

@@ -84,7 +84,11 @@ def run
       installer = Installer.new(@options)
 
       @options[:targets].each do |target|
-        installer.install(target)
+        begin
+          installer.install(target)
+        rescue NotAGitRepoError => e
+          warning "Skipping #{target}: #{e}"
+        end
       end
 
       success 'Installation complete'

lib/overcommit/errors.rb

@@ -0,0 +1,3 @@
+class NotAGitRepoError < StandardError
+  # Nothing to see here
+end

lib/overcommit/installer.rb

@@ -9,9 +9,12 @@ def initialize(options = {})
 
     def install(target)
       absolute_target = File.expand_path(target)
-      unless File.directory?(File.join(absolute_target, '.git'))
+      unless File.directory? absolute_target
+        raise NotAGitRepoError, 'is a directory'
+      end
 
-        raise ArgumentError, "#{target} does not appear to be a git repository"
+      unless File.directory?(File.join(absolute_target, '.git'))
+        raise NotAGitRepoError, 'does not appear to be a git repository'
       end
 
       puts "Installing hooks into #{target}"