Add image_optim as a development dependency

Since we have to `require 'image_optim'` in our tests anyway, add the
`image_optim` gem as a development dependency and remove the class stub.

This still ensures that `overcommit` is decoupled from `image_optim` for
users of Overcommit. For developers, however, it is reasonable to expect
them to have the dependencies of all supported checks so they can run
tests in development.

Also converted some double quotes to single quotes in specs.

Change-Id: I63170434619f5580e3f79ccc7aa6788101e4ca0d
Reviewed-on: https://gerrit.causes.com/30493
Tested-by: jenkins <jenkins@causes.com>
Reviewed-by: Shane da Silva <shane@causes.com>

Author: Shane da Silva

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Overcommit Changelog
 
+## master (unreleased)
+
+* Added pre-commit check that optimizes images with `image_optim`
+
 ## 0.3.2
 
 * Fix bug where `.rubocop.yml` would not be found in present working directory

overcommit.gemspec

@@ -22,4 +22,5 @@ Gem::Specification.new do |s|
             Dir['config/*.yml']
 
   s.add_development_dependency 'rspec', '2.13.0'
+  s.add_development_dependency 'image_optim', '0.9.1'
 end

spec/image_optim.rb

@@ -1,7 +1,7 @@
 require 'spec_helper'
 
 describe Overcommit::GitHook::ImageOptimization::ImageSet do
-  describe "#initialize(image_paths)" do
+  describe '#initialize(image_paths)' do
     let(:path) { '/tmp/filename.jpg20131024-7103-s1d6n9.jpg' }
 
     it "sets the image_paths of the image set" do
@@ -10,12 +10,12 @@
     end
   end
 
-  describe "#optimize_with(ImageOptim)" do
+  describe '#optimize_with(ImageOptim)' do
     let(:optimized_image) { '/tmp/optimized.jpg' }
     let(:unoptimized_image) { '/tmp/unoptimized.jpg' }
     let(:image_optim) { stub('ImageOptim') }
 
-    it "excludes already optimized images from the results" do
+    it 'excludes already optimized images from the results' do
       image_optim.should_receive(:optimize_images!).
         with([unoptimized_image, optimized_image]).
         and_yield(unoptimized_image, true).

spec/plugins/pre_commit/image_optimization/image_set_spec.rb

@@ -8,7 +8,7 @@
     end
   end
 
-  describe "#run_check" do
+  describe '#run_check' do
     let(:image_optim) { stub(ImageOptim) }
     let(:image_set) { stub(described_class::ImageSet) }
     let(:staged_filename) { 'filename.jpg' }
@@ -30,7 +30,7 @@
         and_return(image_set)
     end
 
-    context "when a dependency of image_optim is not installed" do
+    context 'when a dependency of image_optim is not installed' do
       before do
         image_set.
           should_receive(:optimize_with).
@@ -41,7 +41,7 @@
       it { should stop }
     end
 
-    context "when some staged files were optimized" do
+    context 'when some staged files were optimized' do
       before do
         image_set.
           should_receive(:optimize_with).
@@ -52,7 +52,7 @@
       it { should fail_check }
     end
 
-    context "when no staged files were optimized" do
+    context 'when no staged files were optimized' do
       before do
         image_set.
           should_receive(:optimize_with).