Registered NoFragmentCycles validation rule

Author: freshtonic

lib/graphql/validation/rules.ex

@@ -2,12 +2,11 @@
 defmodule GraphQL.Validation.Rules do
 
   # All of the known validation rules.
-  # TODO: it would be great if the rules auto-registered themselves.
-  # A task for a rainy day.
   @rules [
     %GraphQL.Validation.Rules.UniqueOperationNames{},
     %GraphQL.Validation.Rules.FieldsOnCorrectType{},
-    %GraphQL.Validation.Rules.ProvidedNonNullArguments{}
+    %GraphQL.Validation.Rules.ProvidedNonNullArguments{},
+    %GraphQL.Validation.Rules.NoFragmentCycles{}
   ]
 
   def all(), do: @rules