[Analyzer] Cleanup and improve tests for lockfile checkout options.

lib/cocoapods/sandbox.rb

@@ -64,8 +64,12 @@ module Pod
     # @return [Lockfile] the manifest which contains the information about the
     #         installed pods.
     #
+    attr_accessor :manifest
+
     def manifest
-      Lockfile.from_file(manifest_path) if manifest_path.exist?
+      @manifest ||= begin
+        Lockfile.from_file(manifest_path) if manifest_path.exist?
+      end
     end
 
     # @return [Project] the Pods project.

spec/spec_helper.rb

@@ -26,7 +26,9 @@ require 'bacon'
 require 'mocha-on-bacon'
 require 'pretty_bacon'
 require 'pathname'
+
 require 'active_support/core_ext/string/strip'
+require 'active_support/core_ext/object/deep_dup'
 
 ROOT = Pathname.new(File.expand_path('../../', __FILE__))
 $:.unshift((ROOT + 'lib').to_s)