RUBY-1336 Ensure that system collections are not returned from listCollections

Author: estolfo

lib/mongo/operation/list_collections/op_msg.rb

@@ -44,6 +44,11 @@ def execute(server)
 
         private
 
+        def selector(server)
+          (spec[SELECTOR] || {}).merge(
+              listCollections: 1, filter: { name: { '$not' => /system\.|\$/ }})
+        end
+
         def message(server)
           Protocol::Msg.new(flags, options, command(server))
         end

spec/mongo/database_spec.rb

@@ -200,6 +200,10 @@
       it 'returns collection objects for each name' do
         expect(database.collections).to include(collection)
       end
+
+      it 'does not include the system collections' do
+        expect(database.collections.collect(&:name).none? { |name| name =~ /system\.|\$/ }).to be(true)
+      end
     end
 
     context 'when the database does not exist' do