RUBY-304 add Collection#capped?

lib/mongo/collection.rb

@@ -88,6 +88,16 @@ module Mongo
       @hint = nil
     end
 
+    # Indicate whether this is a capped collection.
+    #
+    # @raise [Mongo::OperationFailure]
+    #   if the collection doesn't exist.
+    #
+    # @return [Boolean]
+    def capped?
+      @db.command({:collstats => @name})['capped'] == 1
+    end
+
     # Return a sub-collection of this collection by name. If 'users' is a collection, then
     # 'users.comments' is a sub-collection of users.
     #

test/collection_test.rb

@@ -10,6 +10,16 @@ class TestCollection < Test::Unit::TestCase
     @@test.remove
   end
 
+  def test_capped_method
+    @@db.create_collection('normal')
+    assert !@@db['normal'].capped?
+    @@db.drop_collection('normal')
+
+    @@db.create_collection('c', :capped => true)
+    assert @@db['c'].capped?
+    @@db.drop_collection('c')
+  end
+
   def test_optional_pk_factory
     @coll_default_pk = @@db.collection('stuff')
     assert_equal BSON::ObjectId, @coll_default_pk.pk_factory