1 files changed, 48 insertions, 0 deletions
diff --git a/lib/gitlab/utils/delegator_override.rb b/lib/gitlab/utils/delegator_override.rb
new file mode 100644
index 00000000000..15ba29d3916
--- /dev/null
+++ b/lib/gitlab/utils/delegator_override.rb
@@ -0,0 +1,48 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Utils
+    # This module is to validate that delegator classes (`SimpleDelegator`) do not
+    # accidentally override important logic on the fabricated object.
+    module DelegatorOverride
+      def delegator_target(target_class)
+        return unless ENV['STATIC_VERIFICATION']
+
+        unless self < ::SimpleDelegator
+          raise ArgumentError, "'#{self}' is not a subclass of 'SimpleDelegator' class."
+        end
+
+        DelegatorOverride.validator(self).add_target(target_class)
+      end
+
+      def delegator_override(*names)
+        return unless ENV['STATIC_VERIFICATION']
+        raise TypeError unless names.all? { |n| n.is_a?(Symbol) }
+
+        DelegatorOverride.validator(self).add_allowlist(names)
+      end
+
+      def delegator_override_with(mod)
+        return unless ENV['STATIC_VERIFICATION']
+        raise TypeError unless mod.is_a?(Module)
+
+        DelegatorOverride.validator(self).add_allowlist(mod.instance_methods)
+      end
+
+      def self.validator(delegator_class)
+        validators[delegator_class] ||= Validator.new(delegator_class)
+      end
+
+      def self.validators
+        @validators ||= {}
+      end
+
+      def self.verify!
+        validators.each_value do |validator|
+          validator.expand_on_ancestors(validators)
+          validator.validate_overrides!
+        end
+      end
+    end
+  end
+end