New cop to enforce using new GraphQL types

instead of old ones

.rubocop.yml

@@ -442,6 +442,15 @@ Graphql/JSONType:
     - 'spec/**/*.rb'
     - 'ee/spec/**/*.rb'
 
+Graphql/OldTypes:
+  Enabled: true
+  Include:
+    - 'app/graphql/**/*'
+    - 'ee/app/graphql/**/*'
+  Exclude:
+    - 'spec/**/*.rb'
+    - 'ee/spec/**/*.rb'
+
 RSpec/EnvAssignment:
   Enable: true
   Include:

rubocop/cop/graphql/old_types.rb

+# frozen_string_literal: true
+
+# This cop checks for use of older GraphQL  types in GraphQL fields
+# and arguments.
+# GraphQL::ID_TYPE, GraphQL::INT_TYPE, GraphQL::STRING_TYPE, GraphQL::BOOLEAN_TYPE
+#
+# @example
+#
+#   # bad
+#   class AwfulClass
+#     field :some_field, GraphQL::STRING_TYPE
+#   end
+#
+#   # good
+#   class GreatClass
+#     field :some_field, GraphQL::Types::String
+#   end
+
+module RuboCop
+  module Cop
+    module Graphql
+      class OldTypes < RuboCop::Cop::Cop
+        MSG_ID      = 'Avoid using GraphQL::ID_TYPE. Use GraphQL::Types::ID instead'
+        MSG_INT     = 'Avoid using GraphQL::INT_TYPE. Use GraphQL::Types::Int instead'
+        MSG_STRING  = 'Avoid using GraphQL::STRING_TYPE. Use GraphQL::Types::String instead'
+        MSG_BOOLEAN = 'Avoid using GraphQL::BOOLEAN_TYPE. Use GraphQL::Types::Boolean instead'
+
+        def_node_matcher :has_old_type?, <<~PATTERN
+          (send nil? {:field :argument}
+            (sym _)
+            (const (const nil? :GraphQL) ${:ID_TYPE :INT_TYPE :STRING_TYPE :BOOLEAN_TYPE})
+            (...)?)
+        PATTERN
+
+        def on_send(node)
+          old_constant = has_old_type?(node)
+          return unless old_constant
+
+          add_offense(node, location: :expression, message: "#{self.class}::MSG_#{old_constant[0..-6]}".constantize)
+        end
+      end
+    end
+  end
+end

spec/rubocop/cop/graphql/old_types_spec.rb

+# frozen_string_literal: true
+
+require 'fast_spec_helper'
+require 'rspec-parameterized'
+require_relative '../../../../rubocop/cop/graphql/old_types'
+
+RSpec.describe RuboCop::Cop::Graphql::OldTypes do
+  using RSpec::Parameterized::TableSyntax
+
+  subject(:cop) { described_class.new }
+
+  where(:old_type, :message) do
+    'GraphQL::ID_TYPE'      | 'Avoid using GraphQL::ID_TYPE. Use GraphQL::Types::ID instead'
+    'GraphQL::INT_TYPE'     | 'Avoid using GraphQL::INT_TYPE. Use GraphQL::Types::Int instead'
+    'GraphQL::STRING_TYPE'  | 'Avoid using GraphQL::STRING_TYPE. Use GraphQL::Types::String instead'
+    'GraphQL::BOOLEAN_TYPE' | 'Avoid using GraphQL::BOOLEAN_TYPE. Use GraphQL::Types::Boolean instead'
+  end
+
+  with_them do
+    context 'fields' do
+      it 'adds an offense when an old type is used' do
+        expect_offense(<<~RUBY)
+        class MyType
+          field :some_field, #{old_type}
+          ^^^^^^^^^^^^^^^^^^^#{'^' * old_type.length} #{message}
+        end
+        RUBY
+      end
+
+      it "adds an offense when an old type is used with other keywords" do
+        expect_offense(<<~RUBY)
+        class MyType
+          field :some_field, #{old_type}, null: true, description: 'My description'
+          ^^^^^^^^^^^^^^^^^^^#{'^' * old_type.length}^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ #{message}
+        end
+        RUBY
+      end
+    end
+
+    context 'arguments' do
+      it 'adds an offense when an old type is used' do
+        expect_offense(<<~RUBY)
+        class MyType
+          field :some_arg, #{old_type}
+          ^^^^^^^^^^^^^^^^^#{'^' * old_type.length} #{message}
+        end
+        RUBY
+      end
+
+      it 'adds an offense when an old type is used with other keywords' do
+        expect_offense(<<~RUBY)
+        class MyType
+          argument :some_arg, #{old_type}, null: true, description: 'My description'
+          ^^^^^^^^^^^^^^^^^^^^#{'^' * old_type.length}^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ #{message}
+        end
+        RUBY
+      end
+    end
+  end
+
+  it 'does not add an offense for other types in fields' do
+    expect_no_offenses(<<~RUBY.strip)
+      class MyType
+        field :some_field, GraphQL::Types::JSON
+      end
+    RUBY
+  end
+
+  it 'does not add an offense for other types in arguments' do
+    expect_no_offenses(<<~RUBY.strip)
+      class MyType
+        argument :some_arg, GraphQL::Types::JSON
+      end
+    RUBY
+  end
+
+  it 'does not add an offense for uses outside of field or argument' do
+    expect_no_offenses(<<~RUBY.strip)
+      class MyType
+        foo :some_field, GraphQL::ID_TYPE
+      end
+    RUBY
+  end
+end