[Specification::DSL] Add prepare_command

Closes #1274

CHANGELOG.md

@@ -6,18 +6,22 @@ To install or update CocoaPods see this [guide](http://docs.cocoapods.org/guides
 
 ###### Enhancements
 
-* Added support for resource bundles.  
+* Added `resource_bundles` attribute to Specification DSL.  
   [#743](https://github.com/CocoaPods/CocoaPods/issues/743),
   [#1186](https://github.com/CocoaPods/CocoaPods/issues/1186)
   
-* Added support for bundled frameworks.  
+* Added `vendored_frameworks` attribute to Specification DSL.  
   [#809](https://github.com/CocoaPods/CocoaPods/issues/809),
   [#1075](https://github.com/CocoaPods/CocoaPods/issues/1075)
 
-* Added support for bundled libraries.  
+* Added `vendored_libraries` attribute to Specification DSL.  
   [#809](https://github.com/CocoaPods/CocoaPods/issues/809),
   [#1075](https://github.com/CocoaPods/CocoaPods/issues/1075)
 
+* Added `prepare_command` attribute to Specification DSL. The prepare command
+  will replace the pre_install hook. The post_install hook has been deprecated.  
+  [#1247](https://github.com/CocoaPods/CocoaPods/issues/1247)
+
 * Restructured `.cocoapods` folder to contain repos in a subdirectory.  
   [#1150](https://github.com/CocoaPods/CocoaPods/issues/1150)
   [Ian Ynda-Hummel](https://github.com/ianyh)

lib/cocoapods/installer/pod_source_installer.rb

+require 'active_support/core_ext/string/strip'
+
 module Pod
   class Installer
 
@@ -60,6 +62,7 @@ module Pod
       #
       def install!
         download_source unless predownloaded? || local?
+        run_prepare_command
       end
 
       # Cleans the installations if appropriate.
@@ -106,6 +109,24 @@ module Pod
         end
       end
 
+      extend Executable
+      executable :bash
+
+      # Runs the prepare command bash script of the spec.
+      #
+      # @return [void]
+      #
+      def run_prepare_command
+        return unless root_spec.prepare_command
+        UI.section(" > Running prepare command", '', 1) do
+          Dir.chdir(root) do
+            prepare_command = root_spec.prepare_command.strip_heredoc.chomp
+            full_command = "\nset -e\n" + prepare_command
+            bash!(full_command)
+          end
+        end
+      end
+
       # Removes all the files not needed for the installation according to the
       # specs by platform.
       #

spec/unit/installer/pod_source_installer_spec.rb

@@ -65,6 +65,28 @@ module Pod
 
       #--------------------------------------#
 
+      describe "Prepare command" do
+        it "runs the prepare command if one has been declared in the spec" do
+          @spec.prepare_command = "echo test"
+          @installer.expects(:bash!).once
+          @installer.install!
+        end
+
+        it "doesn't run the prepare command if it hasn't been declared in the spec" do
+          @installer.expects(:bash!).never
+          @installer.install!
+        end
+
+        it "raises if the prepare command fails" do
+          @spec.prepare_command = "missing_command"
+          should.raise Informative do
+            @installer.install!
+          end.message.should.match /command not found/
+        end
+      end
+
+      #--------------------------------------#
+
       describe "Cleaning" do
 
         it "cleans the paths non used by the installation" do