Allow fields with resolvers to not have descriptions

This changes the GraphQL description cop to allow fields to have
all their metadata specified by a resolver.

Allow fields with resolvers not to have descriptions

rubocop/cop/graphql/descriptions.rb

@@ -54,6 +54,10 @@ class Descriptions < RuboCop::Cop::Cop
           (send nil? :value ...)
         PATTERN
 
+        def_node_matcher :resolver_kwarg, <<~PATTERN
+          (... (hash <(pair (sym :resolver) $_) ...>))
+        PATTERN
+
         def_node_matcher :description_kwarg, <<~PATTERN
           (... (hash <(pair (sym :description) $_) ...>))
         PATTERN
@@ -64,6 +68,7 @@ class Descriptions < RuboCop::Cop::Cop
 
         def on_send(node)
           return unless graphql_describable?(node)
+          return if resolver_kwarg(node) # Fields may inherit the description from their resolvers.
 
           description = locate_description(node)
 

spec/rubocop/cop/graphql/descriptions_spec.rb

@@ -6,7 +6,7 @@
 RSpec.describe RuboCop::Cop::Graphql::Descriptions do
   subject(:cop) { described_class.new }
 
-  context 'fields' do
+  context 'with fields' do
     it 'adds an offense when there is no description' do
       expect_offense(<<~TYPE)
         module Types
@@ -46,9 +46,19 @@ class FakeType < BaseObject
         end
       TYPE
     end
+
+    it 'does not add an offense when there is a resolver' do
+      expect_no_offenses(<<~TYPE.strip)
+        module Types
+          class FakeType < BaseObject
+            field :a_thing, resolver: ThingResolver
+          end
+        end
+      TYPE
+    end
   end
 
-  context 'arguments' do
+  context 'with arguments' do
     it 'adds an offense when there is no description' do
       expect_offense(<<~TYPE)
         module Types
@@ -90,7 +100,7 @@ class FakeType < BaseObject
     end
   end
 
-  context 'enum values' do
+  context 'with enum values' do
     it 'adds an offense when there is no description' do
       expect_offense(<<~TYPE)
         module Types