add new CurlPostDownloadStrategy

- lib/cask/url.rb: initialize(): add new `:data` attribute to hold post parameters
- lib/cask/download.rb: perform(): dispatch to new class based on `:using => :post`
- lib/cask/download_strategy.rb: Cask::CurlPostDownloadStrategy:
  			extend curl_args with x-www-form-urlencoded data
- doc/CASK_LANGUAGE_REFERENCE.md: HTTP URLs: document new strategy
- test/cask/test_download_strategy.rb: Cask::CurlPostDownloadStrategy: test new strategy

doc/CASK_LANGUAGE_REFERENCE.md

@@ -184,9 +184,11 @@ of key/value pairs appended to `url`:
 
 | key                | value       |
 | ------------------ | ----------- |
+| `:using`           | the symbol `:post` is the only legal value
 | `:cookies`         | a hash of cookies to be set in the download request
 | `:referer`         | a string holding the URL to set as referrer in the download request
 | `:user_agent`      | a string holding the user agent to set for the download request. Can also be set to the symbol `:fake`, which will use a generic Browser-like user agent string. we prefer `:fake` when the server does not require a specific user agent.
+| `:data`            | a hash of parameters to be set in the POST request
 
 Example: [java.rb](../Casks/java.rb)
 

lib/cask/download.rb

@@ -10,6 +10,8 @@ class Cask::Download
     cask = @cask
     if cask.url.using == :svn
       downloader = Cask::SubversionDownloadStrategy.new(cask)
+    elsif cask.url.using == :post
+      downloader = Cask::CurlPostDownloadStrategy.new(cask)
     else
       downloader = Cask::CurlDownloadStrategy.new(cask)
     end

lib/cask/download_strategy.rb

@@ -77,6 +77,25 @@ class Cask::CurlDownloadStrategy < CurlDownloadStrategy
   end
 end
 
+class Cask::CurlPostDownloadStrategy < Cask::CurlDownloadStrategy
+
+  def curl_args
+    super
+    default_curl_args.concat(post_args)
+  end
+
+  def post_args
+    if cask_url.data
+      # sort_by is for predictability between Ruby versions
+      cask_url.data.sort_by{ |key, value| key.to_s }.map do |key, value|
+        ['-d', "#{CGI.escape(key.to_s)}=#{CGI.escape(value.to_s)}"]
+      end.flatten()
+    else
+      ['-X', 'POST']
+    end
+  end
+end
+
 class Cask::SubversionDownloadStrategy < SubversionDownloadStrategy
   include Cask::DownloadStrategy
 

lib/cask/url.rb

@@ -3,7 +3,7 @@ require 'forwardable'
 class Cask::URL
   FAKE_USER_AGENT = 'Chrome/32.0.1000.00'
 
-  attr_reader :using, :revision, :trust_cert, :uri, :cookies, :referer
+  attr_reader :using, :revision, :trust_cert, :uri, :cookies, :referer, :data
 
   extend Forwardable
   def_delegators :uri, :path, :scheme, :to_s
@@ -16,6 +16,7 @@ class Cask::URL
     @using      = options[:using]
     @revision   = options[:revision]
     @trust_cert = options[:trust_cert]
+    @data       = options[:data]
   end
 
   def user_agent

test/cask/download_strategy_test.rb

@@ -95,6 +95,51 @@ describe Cask::CurlDownloadStrategy do
     shutup { downloader.fetch }
   end
 
+  describe Cask::CurlPostDownloadStrategy do
+    it 'properly assigns a name and Resource based on the cask' do
+      cask = Cask.load('basic-cask')
+
+      downloader = Cask::CurlPostDownloadStrategy.new(BasicCask)
+      downloader.name.must_equal 'basic-cask'
+      downloader.resource.name.must_equal 'basic-cask'
+      downloader.resource.url.must_equal cask.url.to_s
+      downloader.resource.version.to_s.must_equal cask.version
+    end
+
+    it 'adds curl args for post arguments' do
+      WithPostArgs = Class.new(Cask) do
+        url 'http://host/path/to/form.html', :data => {
+              :coo => 'kie',
+              :mon => 'ster'
+            }, :using => :post
+        version '1.2.3.4'
+      end
+
+      downloader = Cask::CurlPostDownloadStrategy.new(WithPostArgs)
+      downloader.temporary_path.stubs(:rename)
+      downloader.expects(:curl).with do |*args|
+        # includes_args tests set membership;
+        # repeated options don't pass the test
+        includes_args?(args, ['-d', 'coo=kie', 'mon=ster'])
+      end
+      shutup { downloader.fetch }
+    end
+
+    it 'adds curl args for post arguments with no :data' do
+      WithoutPostArgs = Class.new(Cask) do
+        url 'http://host/path/to/form.html', :using => :post
+        version '1.2.3.4'
+      end
+
+      downloader = Cask::CurlPostDownloadStrategy.new(WithoutPostArgs)
+      downloader.temporary_path.stubs(:rename)
+      downloader.expects(:curl).with do |*args|
+        includes_args?(args, ['-X', 'POST'])
+      end
+      shutup { downloader.fetch }
+    end
+  end
+
   describe Cask::SubversionDownloadStrategy do
     it 'recognizes the SVN download strategy' do
       cask = Cask.load('svn-download-cask')