Support multiple platforms in a gem.deps.rb

Bundler supports multiple platforms but this was not implemented for
gem.deps.rb.  Now RubyGems supports multiple platforms.

Fixes #821

History.txt

@@ -35,6 +35,8 @@ Bug fixes:
   Aaron Patterson.
 * Commands using the rubygems.org API no longer try to sign-in when a
   non-rubygems API key has been chosen.  Bug #826 by Ben Sedat.
+* Gem dependency API supports multiple platforms for #platform and #platforms
+  now.  Bug #821 by johnny5-.
 * The environment command now shows the system configuration directory where
   the all-users gemrc lives.  Bug #827 by Ben Langfeld.
 * Improved speed of conflict checking when activating gems.  Pull request #843

lib/rubygems/request_set/gem_dependency_api.rb

@@ -136,7 +136,7 @@ def initialize set, path
     @path = path
 
     @current_groups     = nil
-    @current_platform   = nil
+    @current_platforms  = nil
     @current_repository = nil
     @default_sources    = true
     @git_set            = @set.git_set
@@ -315,7 +315,7 @@ def gem_path name, options # :nodoc:
 
   def gem_platforms options # :nodoc:
     platform_names = Array(options.delete :platforms)
-    platform_names << @current_platform if @current_platform
+    platform_names.concat @current_platforms if @current_platforms
 
     return true if platform_names.empty?
 
@@ -442,13 +442,13 @@ def pin_gem_source name, type = :default, source = nil
   #
   # Block form for restricting gems to a particular platform.
 
-  def platform what
-    @current_platform = what
+  def platform *platforms
+    @current_platforms = platforms
 
     yield
 
   ensure
-    @current_platform = nil
+    @current_platforms = nil
   end
 
   ##

test/rubygems/test_gem_request_set_gem_dependency_api.rb

@@ -555,6 +555,28 @@ def test_platform_mswin
     Gem.win_platform = win_platform
   end
 
+  def test_platform_multiple
+    win_platform, Gem.win_platform = Gem.win_platform?, false
+
+    with_engine_version 'ruby', '1.8.7' do
+      @gda.platform :mri_19, :mri_20 do
+        @gda.gem 'a'
+      end
+    end
+
+    assert_empty @set.dependencies
+
+    with_engine_version 'ruby', '2.0.0' do
+      @gda.platform :mri_19, :mri_20 do
+        @gda.gem 'a'
+      end
+    end
+
+    refute_empty @set.dependencies
+  ensure
+    Gem.win_platform = win_platform
+  end
+
   def test_platform_ruby
     win_platform, Gem.win_platform = Gem.win_platform?, false