Import EnforceSuperclass module

lib/rubocop/cop/mixin/enforce_superclass.rb

@@ -0,0 +1,32 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module Cop
+    # Common functionality for enforcing a specific superclass.
+    module EnforceSuperclass
+      def self.included(base)
+        base.def_node_matcher :class_definition, <<~PATTERN
+          (class (const _ !:#{base::SUPERCLASS}) #{base::BASE_PATTERN} ...)
+        PATTERN
+
+        base.def_node_matcher :class_new_definition, <<~PATTERN
+          [!^(casgn {nil? cbase} :#{base::SUPERCLASS} ...)
+           !^^(casgn {nil? cbase} :#{base::SUPERCLASS} (block ...))
+           (send (const {nil? cbase} :Class) :new #{base::BASE_PATTERN})]
+        PATTERN
+      end
+
+      def on_class(node)
+        class_definition(node) do
+          add_offense(node.children[1])
+        end
+      end
+
+      def on_send(node)
+        class_new_definition(node) do
+          add_offense(node.children.last)
+        end
+      end
+    end
+  end
+end