diff --git a/lib/sashimi/repositories/abstract_repository.rb b/lib/sashimi/repositories/abstract_repository.rb
index 1b6786d..82f7e5e 100644
--- a/lib/sashimi/repositories/abstract_repository.rb
+++ b/lib/sashimi/repositories/abstract_repository.rb
@@ -1,8 +1,7 @@
 module Sashimi
   class PluginNotFound < StandardError #:nodoc:
     def initialize(plugin_name, message = nil)
-      @plugin_name = plugin_name
-      @message     = message
+      @plugin_name, @message = plugin_name, message
     end
 
     def to_s
@@ -23,10 +22,11 @@ def initialize(plugin)
     
     # Remove the repository
     def uninstall
-      change_dir_to_local_repository
-      raise PluginNotFound.new(plugin.name) unless File.exists?(plugin.name)
-      FileUtils.rm_rf(plugin.name)
-      remove_from_cache
+      with_path local_repository_path do
+        raise PluginNotFound.new(plugin.name) unless File.exists?(plugin.name)
+        FileUtils.rm_rf(plugin.name)
+        remove_from_cache
+      end
     end
     
     # Add to a Rails app.
@@ -45,11 +45,13 @@ def copy_plugin_and_remove_hidden_folders
 
     class << self
       def instantiate_repository(plugin)
-        unless plugin.name.nil?
-          instantiate_repository_by_cache(plugin)
-        else
-          instantiate_repository_by_url(plugin)
-        end.new(plugin)
+        with_path local_repository_path do
+          unless plugin.name.nil?
+            instantiate_repository_by_cache(plugin)
+          else
+            instantiate_repository_by_url(plugin)
+          end.new(plugin)
+        end
       end
 
       # Return all installed plugin names and summary, formatted for stdout.
@@ -66,20 +68,22 @@ def plugins_names
 
       # Update the plugins installed in a rails app.
       def update_rails_plugins(plugins_names)
-        change_dir(path_to_rails_app)
-        if under_version_control?
-          update_versioned_rails_plugins(plugins_names)
-        else
-          update_unversioned_rails_plugins(plugins_names)
+        with_path path_to_rails_app do
+          if under_version_control?
+            update_versioned_rails_plugins(plugins_names)
+          else
+            update_unversioned_rails_plugins(plugins_names)
+          end
         end
       end
 
       # Update the plugins installed in a non versioned rails app.
       def update_unversioned_rails_plugins(plugins_names)
-        change_dir(plugins_dir)
-        plugins_names.each do |plugin_name|
-          FileUtils.rm_rf(plugin_name)
-          Plugin.new(plugin_name).add
+        with_path plugins_dir do
+          plugins_names.each do |plugin_name|
+            FileUtils.rm_rf(plugin_name)
+            Plugin.new(plugin_name).add
+          end
         end
       end
 
@@ -126,8 +130,9 @@ def path_to_rails_app
 
       # Read the cache file and return the content as an <tt>Hash</tt>.
       def cache_content
-        change_dir_to_local_repository
-        @@cache_content ||= (YAML::load_file(cache_file) || {}).to_hash
+        with_path local_repository_path do
+          @@cache_content ||= (YAML::load_file(cache_file) || {}).to_hash
+        end
       end
 
       def instantiate_repository_by_url(plugin)
@@ -139,26 +144,17 @@ def instantiate_repository_by_cache(plugin)
         raise PluginNotFound.new(plugin.name) if cached_plugin.nil?
         cached_plugin['type'] == 'git' ? GitRepository : SvnRepository
       end
-
-      # Changes the current directory with the given one
-      def change_dir(dir)
-        FileUtils.cd(dir)
-      end
-      
-      # Change the current directory with local_repository_path
-      def change_dir_to_local_repository
-        change_dir(local_repository_path)
-      end
-      
+            
       # Change the current directory with the fully qualified
       # path to Rails app and plugins_dir.
-      def change_dir_to_absolute_plugins_dir
-        change_dir(File.join(File.expand_path(path_to_rails_app), plugins_dir))
+      def absolute_rails_plugins_path
+        @@absolute_rails_plugins_path ||= File.join(File.expand_path(path_to_rails_app),
+          rails_plugins_path)
       end
       
       # Rails app plugins dir
-      def plugins_dir
-        @@plugins_dir ||= File.join('vendor', 'plugins')
+      def rails_plugins_path
+        @@rails_plugins_path ||= File.join('vendor', 'plugins')
       end
       
       # Check if the current working directory is under version control
@@ -194,6 +190,16 @@ def find_home
       def git_url?(url)
         url =~ /^git:\/\// || url =~ /\.git$/
       end
+      
+      def with_path(path, &block)
+        begin
+          old_path = Dir.pwd
+          FileUtils.cd(path)
+          yield
+        ensure
+          FileUtils.cd(old_path)
+        end
+      end
     end
 
     # Return the SCM type
@@ -207,46 +213,51 @@ def scm_type
     # Read the content of the <tt>about.yml</tt>.
     # New feature of Rails 2.1.x http:://dev.rubyonrails.org/changeset/9098
     def about
-      change_dir_to_plugin_path
-      return {} unless File.exists?('about.yml')
-      (YAML::load_file('about.yml') || {}).to_hash
+      with_path plugin_path do
+        return {} unless File.exists?('about.yml')
+        (YAML::load_file('about.yml') || {}).to_hash
+      end
     end
 
     # Returns a list of files that should be scheduled for SCM add.
     def files_scheduled_for_add
-      change_dir_to_absolute_plugins_dir
-      Dir[plugin.name+"-tmp/**/*"].collect {|fn| fn.gsub(plugin.name+'-tmp', '.')} -
-        Dir[plugin.name+"/**/*"].collect{|fn| fn.gsub(plugin.name, '.')}
+      with_path absolute_rails_plugins_path do
+        Dir[plugin.name+"-tmp/**/*"].collect {|fn| fn.gsub(plugin.name+'-tmp', '.')} -
+          Dir[plugin.name+"/**/*"].collect{|fn| fn.gsub(plugin.name, '.')}
+      end
     end
     
     # Returns a list of files that should be scheduled for SCM remove.
     def files_scheduled_for_remove
-      change_dir_to_absolute_plugins_dir
-      Dir[plugin.name+"/**/*"].collect {|fn| fn.gsub(plugin.name, '.')} -
-        Dir[plugin.name+"-tmp/**/*"].collect {|fn| fn.gsub(plugin.name+"-tmp", '.')}
+      with_path absolute_rails_plugins_path do
+        Dir[plugin.name+"/**/*"].collect {|fn| fn.gsub(plugin.name, '.')} -
+          Dir[plugin.name+"-tmp/**/*"].collect {|fn| fn.gsub(plugin.name+"-tmp", '.')}
+      end
     end
     
     # Remove the temp folder, used by update process.
     def remove_temp_folder
-      change_dir_to_absolute_plugins_dir
-      FileUtils.rm_rf(plugin.name+'-tmp')
+      with_path absolute_rails_plugins_path do
+        FileUtils.rm_rf(plugin.name+'-tmp')
+      end
     end
     
-    class_method_proxy :change_dir, :change_dir_to_local_repository,
-      :change_dir_to_absolute_plugins_dir, :local_repository_path,
-      :cache_file, :cache_content, :plugins_dir, :path_to_rails_app
+    class_method_proxy :local_repository_path, :cache_file,
+      :cache_content, :path_to_rails_app, :rails_plugins_path,
+      :with_path
 
   private
-    # Change the current directory with the plugin one
-    def change_dir_to_plugin_path
-      change_dir(File.join(local_repository_path, plugin.name || plugin.guess_name))
+    # Returns the path to the plugin
+    def plugin_path
+      File.join(local_repository_path, plugin.name || plugin.guess_name)
     end
 
     # Prepare the plugin installation
     def prepare_installation
       FileUtils.mkdir_p(local_repository_path)
-      change_dir_to_local_repository
-      FileUtils.touch(cache_file)
+      with_path local_repository_path do
+        FileUtils.touch(cache_file)
+      end
     end
     
     # Add a plugin into the cache
@@ -262,17 +273,20 @@ def remove_from_cache
 
     # Write all the plugins into the cache
     def write_to_cache(plugins)
-      change_dir_to_local_repository
-      FileUtils.mv(cache_file, "#{cache_file}-backup")
-      File.open(cache_file, 'w'){|f| f.write(plugins.to_yaml)}
-      FileUtils.rm("#{cache_file}-backup")
+      with_path local_repository_path do
+        FileUtils.mv(cache_file, "#{cache_file}-backup")
+        File.open(cache_file, 'w'){|f| f.write(plugins.to_yaml)}
+        FileUtils.rm("#{cache_file}-backup")
+      end
     end
     
     # Copy a plugin to a Rails app.
     def copy_plugin_to_rails_app
-      change_dir(path_to_rails_app)
-      FileUtils.mkdir_p(plugins_dir)
-      FileUtils.cp_r(File.join(local_repository_path, plugin.name), File.join(plugins_dir, plugin.name+'-tmp'))
+      with_path path_to_rails_app do
+        FileUtils.mkdir_p(plugins_path)
+        FileUtils.cp_r(File.join(local_repository_path, plugin.name),
+          File.join(plugins_path, plugin.name+'-tmp'))
+      end
     end
     
     # Rename the *-tmp folder used by the installation process.
@@ -280,18 +294,21 @@ def copy_plugin_to_rails_app
     # Example:
     #   click-to-globalize-tmp # => click-to-globalize
     def rename_temp_folder
-      change_dir(path_to_rails_app)
-      FileUtils.mv(File.join(plugins_dir, plugin.name+'-tmp'), File.join(plugins_dir, plugin.name))
+      with_path path_to_rails_app do
+        FileUtils.mv(File.join(plugins_dir, plugin.name+'-tmp'),
+          File.join(plugins_dir, plugin.name))
+      end
     end
     
     # Remove SCM hidden folders.
     def remove_hidden_folders
       require 'find'
-      change_dir(File.join(path_to_rails_app, plugins_dir, plugin.name+'-tmp'))
-      Find.find('./') do |path|
-        if File.basename(path) == '.'+scm_type
-          FileUtils.remove_dir(path, true)
-          Find.prune
+      with_path File.join(absolute_rails_plugins_path, plugin.name + '-tmp') do
+        Find.find('./') do |path|
+          if File.basename(path) == '.'+scm_type
+            FileUtils.remove_dir(path, true)
+            Find.prune
+          end
         end
       end
     end
diff --git a/lib/sashimi/repositories/git_repository.rb b/lib/sashimi/repositories/git_repository.rb
index a154a7b..c13c1b6 100644
--- a/lib/sashimi/repositories/git_repository.rb
+++ b/lib/sashimi/repositories/git_repository.rb
@@ -9,8 +9,9 @@ def install
     
     def update
       puts plugin.name.titleize + "\n\n"
-      change_dir_to_plugin_path
-      Kernel.system('git pull')
+      with_path plugin_path do
+        Kernel.system('git pull')
+      end
     end
   end
 end
diff --git a/lib/sashimi/repositories/svn_repository.rb b/lib/sashimi/repositories/svn_repository.rb
index bbfbb49..26b8822 100644
--- a/lib/sashimi/repositories/svn_repository.rb
+++ b/lib/sashimi/repositories/svn_repository.rb
@@ -9,8 +9,9 @@ def install
     
     def update
       puts plugin.name.titleize + "\n\n"
-      change_dir_to_plugin_path
-      Kernel.system("svn up")
+      with_path plugin_path do
+        Kernel.system("svn up")
+      end
     end
   end
 end
diff --git a/test/test_helper.rb b/test/test_helper.rb
index 73a6a1f..3ce97e7 100644
--- a/test/test_helper.rb
+++ b/test/test_helper.rb
@@ -9,12 +9,27 @@ def assert_not(condition, message = nil)
   end
   
 private
-  def initialize_repository_for_test(&block)
-    repository.prepare_installation
-    create_cache_file
-    create_plugin_directories
-    yield
-    remove_local_repository_path # make sure of clean up tmp dirs
+  def create_test_repository
+    prepare_installation
+    with_path plugins_path do
+      create_cache_file
+      create_plugin_directories
+    end
+  end
+
+  def destroy_test_repository
+    FileUtils.rm_rf(local_repository_path)
+  end
+
+  alias_method :setup, :create_test_repository
+  alias_method :teardown, :destroy_test_repository
+
+  def local_repository_path
+    @local_repository_path ||= File.join(repository.class.find_home, 'sashimi_test')
+  end
+
+  def plugins_path
+    @plugins_path ||= File.join(local_repository_path, '.rails', 'plugins')
   end
 
   def repository
@@ -22,7 +37,7 @@ def repository
   end
 
   def create_repository(plugin_name = 'sashimi', url = 'git://github.com/jodosha/sashimi.git')
-    @repository ||= AbstractRepository.new(Plugin.new(plugin_name, url))
+    AbstractRepository.new(Plugin.new(plugin_name, url))
   end
 
   def plugin
@@ -39,6 +54,10 @@ def cached_plugin
       'plug-in' => {'type' => 'svn'} }
   end
 
+  def cache_file
+    '.plugins'
+  end
+
   def create_plugin_directories
     { 'plugin' => true, 'plug-in' => false }.each do |plugin, about|
       create_plugin_directory(plugin, about)
@@ -46,32 +65,44 @@ def create_plugin_directories
   end
 
   def create_plugin_directory(plugin, about = true)
-    AbstractRepository.change_dir_to_local_repository
     FileUtils.mkdir(plugin) unless File.exists?(plugin)
     FileUtils.cd(plugin)
     File.open('about.yml', 'w+'){|f| f.write({'summary' => "Plugin summary"}.to_yaml)} if about
-    AbstractRepository.change_dir_to_local_repository
   end
 
-  def create_cache_file
-    File.open(repository.cache_file, 'w+'){|f| f.write(cached_plugin.to_yaml)}
+  def prepare_installation
+    FileUtils.mkdir_p(plugins_path)
   end
 
-  def remove_local_repository_path
-    FileUtils.rm_rf(File.join(repository.class.find_home, 'sashimi_test'))
-  end  
+  def create_cache_file
+    File.open(cache_file, 'w+'){|f| f.write(cached_plugin.to_yaml)}
+  end
+  
+  def with_local_repository_path(&block)
+    with_path(local_repository_path, &block)
+  end
+  
+  # FIXME why often Dir.pwd returns nil ?
+  def with_path(path, &block)
+    begin
+      old_path = Dir.pwd rescue plugins_path
+      FileUtils.cd(path)
+      yield
+    ensure
+      FileUtils.cd(old_path)
+    end
+  end
 end
 
 module Sashimi
   class AbstractRepository
     @@local_repository_sub_path = 'sashimi_test/.rails/plugins'
+    cattr_accessor :local_repository_sub_path
     public :add_to_cache, :cache_content, :cache_file,
-      :change_dir, :change_dir_to_absolute_plugins_dir,
-      :change_dir_to_local_repository, :change_dir_to_plugin_path,
       :copy_plugin_to_rails_app, :local_repository_path, :path_to_rails_app,
-      :plugins_dir, :prepare_installation, :remove_from_cache,
+      :prepare_installation, :remove_from_cache, :rails_plugins_path,
       :remove_hidden_folders, :rename_temp_folder, :run_install_hook,
-      :write_to_cache
+      :write_to_cache, :with_path, :plugin_path
   end
 end
 
diff --git a/test/unit/plugin_test.rb b/test/unit/plugin_test.rb
index 51e784d..270270f 100644
--- a/test/unit/plugin_test.rb
+++ b/test/unit/plugin_test.rb
@@ -30,9 +30,7 @@ def test_should_instantiate_svn_repository_for_not_git_url
   end
   
   def test_should_serialize_to_hash
-    initialize_repository_for_test do
-      expected = {'plugin' => {'type' => 'svn', 'summary' => 'Plugin summary'}}
-      assert_equal(expected, create_plugin('plugin', 'http://dev.repository.com/svn/plugin/trunk').to_hash)
-    end
+    expected = {'plug-in' => {'type' => 'svn', 'summary' => nil}}
+    assert_equal(expected, create_plugin('plug-in', 'http://dev.repository.com/svn/plug-in/trunk').to_hash)
   end
 end
diff --git a/test/unit/repositories/abstract_repository_test.rb b/test/unit/repositories/abstract_repository_test.rb
index 7b4fa77..fd03d3b 100644
--- a/test/unit/repositories/abstract_repository_test.rb
+++ b/test/unit/repositories/abstract_repository_test.rb
@@ -2,125 +2,99 @@
 require 'test/test_helper'
 
 class AbstractRepositoryTest < Test::Unit::TestCase
-  def test_initialize
-    assert repository
-    assert repository.plugin.name
-    assert repository.plugin.url
-  end
-  
-  # CLASS CONSTANTS
-  def test_local_repository_path
-    assert_match(/\.rails\/plugins$/, repository.local_repository_path)
-  end
-  
-  def test_cache_file
-    assert_equal(".plugins", repository.cache_file)
-  end
+  uses_mocha 'AbstractRepositoryTest' do
+    def test_initialize
+      assert repository
+      assert repository.plugin.name
+      assert repository.plugin.url
+    end
 
-  def test_plugins_dir
-    assert_equal('vendor/plugins', repository.plugins_dir)
-  end
+    # CLASS CONSTANTS
+    def test_local_repository_path
+      assert_match(/\.rails\/plugins$/, repository.local_repository_path)
+    end
 
-  # INSTANTIATE
-  def test_should_instantiate_repository_by_url
-    assert_kind_of(SvnRepository, AbstractRepository.instantiate_repository(create_plugin(nil, 'http://svn.com')))
-    assert_kind_of(GitRepository, AbstractRepository.instantiate_repository(plugin))
-  end
-  
-  def test_should_instantiate_repository_by_cache
-    initialize_repository_for_test do
-      assert AbstractRepository.instantiate_repository(create_plugin('sashimi', ''))
+    def test_cache_file
+      assert_equal(".plugins", repository.cache_file)
     end
-  end
-  
-  def test_should_recognize_git_url
-    assert AbstractRepository.git_url?('git://github.com/jodosha/sashimi.git')
-  end
-  
-  # COMMANDS
-  def test_should_list_all_installed_plugins
-    initialize_repository_for_test do
+
+    def test_plugins_path
+      assert_equal('vendor/plugins', repository.rails_plugins_path)
+    end
+
+    # INSTANTIATE
+    def test_should_instantiate_repository_by_url
+      assert_kind_of(SvnRepository, AbstractRepository.instantiate_repository(create_plugin(nil, 'http://svn.com')))
+      assert_kind_of(GitRepository, AbstractRepository.instantiate_repository(plugin))
+    end
+
+    def test_should_instantiate_repository_by_cache
+      assert AbstractRepository.instantiate_repository(create_plugin('plugin', ''))
+    end
+
+    def test_should_recognize_git_url
+      assert AbstractRepository.git_url?('git://github.com/jodosha/sashimi.git')
+    end
+
+    # COMMANDS
+    def test_should_list_all_installed_plugins
       assert_equal("plug-in\t\t\nplugin\t\t\nsashimi\t\t", AbstractRepository.list)
     end
-  end
-  
-  def test_should_return_all_installed_plugins_names
-    initialize_repository_for_test do
+
+    def test_should_return_all_installed_plugins_names
       assert_equal(['plug-in', 'plugin'], AbstractRepository.plugins_names)
     end
-  end
-  
-  # DIRECTORIES
-  def test_should_change_current_dir
-    repository.change_dir(repository.class.find_home)
-    assert_equal(repository.class.find_home, Dir.pwd)
-  end
-  
-  def test_should_change_current_dir_with_local_repository_path
-    initialize_repository_for_test do
-      repository.change_dir_to_local_repository
-      assert_equal(repository.local_repository_path, Dir.pwd)
+
+    def test_should_uninstall_plugin
+      Dir.stubs(:pwd).returns repository.class.find_home
+      r = create_repository('plugin', '')
+      r.uninstall
+      assert_not repository.cache_content.keys.include?('plugin')
     end
-  end
-  
-  def test_should_change_current_dir_with_plugin_cache_path
-    initialize_repository_for_test do
-      FileUtils.mkdir_p(cached_plugin_path)
-      repository.change_dir_to_plugin_path
-      assert_equal(cached_plugin_path, Dir.pwd)
+
+    def test_should_raise_exception_if_plugin_was_not_found
+      Dir.stubs(:pwd).returns repository.class.find_home
+      assert_raise(Sashimi::PluginNotFound) { repository.uninstall }
     end
-  end
-  
-  def _ignore_test_should_copy_plugin_to_a_rails_app
-    initialize_repository_for_test do
+
+    # DIRECTORIES
+    def _ignore_test_should_copy_plugin_to_a_rails_app
       repository.change_dir_to_local_repository
       create_repository('plugin', '').copy_plugin_to_rails_app
       assert File.exists?(File.join('vendor', 'plugins', 'plugin', 'about.yml'))
     end
-  end
-  
-  # REPOSITORY
-  def test_should_prepare_installation
-    initialize_repository_for_test do
+
+    # REPOSITORY
+    def test_should_prepare_installation
       assert File.exists?(repository.local_repository_path)
+      Dir.expects(:pwd).returns plugins_path
       assert_equal(repository.local_repository_path, Dir.pwd)
       assert File.exists?(repository.cache_file)
     end
-  end
 
-  # CACHE
-  def test_should_read_cache_content
-    initialize_repository_for_test do
+    # CACHE
+    def test_should_read_cache_content
       assert_equal(cache_content, repository.cache_content)
     end
-  end
-  
-  def test_should_add_plugin_to_the_cache
-    initialize_repository_for_test do
+
+    def test_should_add_plugin_to_the_cache
       expected = cache_content.merge(cached_plugin)
       repository.add_to_cache(cached_plugin)
       assert_equal expected, cache_content
     end
-  end
-  
-  def test_should_remove_plugin_from_cache
-    initialize_repository_for_test do
+
+    def test_should_remove_plugin_from_cache
       AbstractRepository.new(create_plugin('sashimi', '')).remove_from_cache
       assert_equal({"plugin"=>{"type"=>"svn"}, "plug-in"=>{"type"=>"svn"}}, cache_content)
     end
-  end
-  
-  # ABOUT
-  def test_should_return_about_contents_from_about_yml
-    initialize_repository_for_test do
+
+    # ABOUT
+    def test_should_return_about_contents_from_about_yml
       plugin = create_plugin('plugin', 'http://dev.repository.com/svn/plugin/trunk')
       assert_equal({'summary' => "Plugin summary"}, plugin.about)
     end
-  end
-  
-  def test_should_return_empty_hash_for_unexstistent_about_yml
-    initialize_repository_for_test do
-      
+
+    def test_should_return_empty_hash_for_unexstistent_about_yml
       plugin = create_plugin('plug-in', 'http://dev.repository.com/svn/plug-in/trunk')
       assert_equal({}, plugin.about)
     end
diff --git a/test/unit/repositories/git_repository_test.rb b/test/unit/repositories/git_repository_test.rb
index 087d3a3..edb94d0 100644
--- a/test/unit/repositories/git_repository_test.rb
+++ b/test/unit/repositories/git_repository_test.rb
@@ -20,7 +20,7 @@ def test_should_raise_exception_for_non_repository_url
     end
     
     def test_should_create_git_repository
-      initialize_repository_for_test do
+      repository.with_path plugins_path do
         FileUtils.mkdir_p('sashimi')
         Kernel.expects(:system).with('git clone git://github.com/jodosha/sashimi.git')
         GitRepository.new(plugin).install
diff --git a/test/unit/repositories/svn_repository_test.rb b/test/unit/repositories/svn_repository_test.rb
index 408a723..8536fc3 100644
--- a/test/unit/repositories/svn_repository_test.rb
+++ b/test/unit/repositories/svn_repository_test.rb
@@ -19,8 +19,8 @@ def test_should_raise_exception_for_non_repository_url
       assert_raise(Errno::ENOENT) { repository.install }      
     end
     
-    def test_should_create_git_repository
-      initialize_repository_for_test do
+    def test_should_create_svn_repository
+      repository.with_path plugins_path do
         FileUtils.mkdir_p('sashimi')
         Kernel.expects(:system).with('svn co http://dev.repository.com/svn/sashimi/trunk sashimi')
         SvnRepository.new(create_plugin(nil, 'http://dev.repository.com/svn/sashimi/trunk')).install