Add BaseEdge base class

See https://gitlab.com/gitlab-org/gitlab/-/issues/341911

This adds a new base class for edges that uses our custom `BaseField`
as the standard field class.

We do not need to customize authorization for edges, since nodes are
redacted by our connections before edges are constructed from them.

All our edges should inherit from this base class in order to use field
customizations.

Changelog: changed

app/graphql/types/base_edge.rb

+# frozen_string_literal: true
+
+module Types
+  class BaseEdge < GraphQL::Types::Relay::BaseEdge
+    field_class Types::BaseField
+  end
+end

app/graphql/types/base_field.rb

@@ -78,6 +78,8 @@ module Types
     attr_reader :feature_flag
 
     def field_authorized?(object, ctx)
+      object = object.node if object.is_a?(GraphQL::Pagination::Connection::Edge)
+
       authorization.ok?(object, ctx[:current_user])
     end
 

rubocop/cop/graphql/authorize_types.rb

@@ -8,7 +8,7 @@ module RuboCop
               'https://docs.gitlab.com/ee/development/api_graphql_styleguide.html#type-authorization'
 
         # We want to exclude our own basetypes and scalars
-        ALLOWED_TYPES = %w[BaseEnum BaseScalar BasePermissionType MutationType SubscriptionType
+        ALLOWED_TYPES = %w[BaseEnum BaseEdge BaseScalar BasePermissionType MutationType SubscriptionType
                            QueryType GraphQL::Schema BaseUnion BaseInputObject].freeze
 
         def_node_search :authorize?, <<~PATTERN

spec/graphql/types/base_edge_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe Types::BaseEdge do
+  include GraphqlHelpers
+
+  let_it_be(:test_schema) do
+    project_edge_type = Class.new(described_class) do
+      field :proof_of_admin_rights, String,
+            null: true, authorize: :admin_project
+
+      def proof_of_admin_rights
+        'ok'
+      end
+    end
+
+    project_type = Class.new(::Types::BaseObject) do
+      graphql_name 'Project'
+      authorize :read_project
+      edge_type_class project_edge_type
+
+      field :name, String, null: false
+    end
+
+    Class.new(GraphQL::Schema) do
+      lazy_resolve ::Gitlab::Graphql::Lazy, :force
+      use ::GraphQL::Pagination::Connections
+      use ::Gitlab::Graphql::Pagination::Connections
+
+      query(Class.new(::Types::BaseObject) do
+        graphql_name 'Query'
+        field :projects, project_type.connection_type, null: false
+
+        def projects
+          context[:projects]
+        end
+      end)
+    end
+  end
+
+  def document
+    GraphQL.parse(<<~GQL)
+    query {
+      projects {
+        edges {
+          proofOfAdminRights
+          node { name }
+        }
+      }
+    }
+    GQL
+  end
+
+  it 'supports field authorization on edge fields' do
+    user = create(:user)
+    private_project = create(:project, :private)
+    member_project = create(:project, :private)
+    maintainer_project = create(:project, :private)
+    public_project = create(:project, :public)
+
+    member_project.add_developer(user)
+    maintainer_project.add_maintainer(user)
+    projects = [private_project, member_project, maintainer_project, public_project]
+
+    data = { current_user: user, projects: projects }
+    query = GraphQL::Query.new(test_schema, document: document, context: data)
+    result = query.result.to_h
+
+    expect(graphql_dig_at(result, 'data', 'projects', 'edges', 'node', 'name'))
+      .to contain_exactly(member_project.name, maintainer_project.name, public_project.name)
+
+    expect(graphql_dig_at(result, 'data', 'projects', 'edges', 'proofOfAdminRights'))
+      .to contain_exactly('ok')
+  end
+end