new experimental check: gems that contain a DLL but platform is set t…

…o ruby

* gems containing DLLs are procompiled extensions that target windows.
  The plaform should be set to a win32 variant

README.rdoc

@@ -49,7 +49,6 @@ Full source is on github at https://github.com/yob/gem-lint
 
 == Ideas for new checks
 
-* look for gems containing DLLs with platform ruby
 * improved handling of compiled extensions
 * files entry in spec not matching actual files in data
 

lib/gem_lint/strategies/ruby_platform_with_dll_strategy.rb

@@ -0,0 +1,35 @@
+module GemLint
+  module Strategies
+    class RubyPlatformWithDllStrategy < AbstractStrategy
+
+      def description
+        "contains a DLL for windows, but platform is set to ruby"
+      end
+
+      def tag
+        :"ruby-platform-with-dll"
+      end
+
+      def level
+        :warning
+      end
+
+      def fail?
+        contains_dll? && spec.platform == "ruby"
+      end
+
+      private
+
+      def contains_dll?
+        spec.files.any? { |file|
+          file.downcase[-4,4] == ".dll"
+        }
+      end
+
+      def spec
+        @spec ||= YAML.load(File.read(@metadata_path))
+      end
+
+    end
+  end
+end