1 files changed, 53 insertions, 0 deletions
diff --git a/rubocop/cop/api/base.rb b/rubocop/cop/api/base.rb
new file mode 100644
index 00000000000..85b19e9a833
--- /dev/null
+++ b/rubocop/cop/api/base.rb
@@ -0,0 +1,53 @@
+# frozen_string_literal: true
+
+module RuboCop
+  module Cop
+    module API
+      class Base < RuboCop::Cop::Cop
+        # This cop checks that APIs subclass API::Base.
+        #
+        # @example
+        #
+        # # bad
+        # module API
+        #   class Projects < Grape::API
+        #   end
+        # end
+        #
+        # module API
+        #   class Projects < Grape::API::Instance
+        #   end
+        # end
+        #
+        # # good
+        # module API
+        #   class Projects < ::API::Base
+        #   end
+        # end
+        MSG = 'Inherit from ::API::Base instead of Grape::API::Instance or Grape::API. ' \
+              'For more details check https://gitlab.com/gitlab-org/gitlab/-/issues/215230.'
+
+        def_node_matcher :grape_api, '(const (const {nil? (cbase)} :Grape) :API)'
+        def_node_matcher :grape_api_definition, <<~PATTERN
+          (class
+            (const _ _)
+            {#grape_api (const #grape_api :Instance)}
+            ...
+          )
+        PATTERN
+
+        def on_class(node)
+          grape_api_definition(node) do
+            add_offense(node.children[1])
+          end
+        end
+
+        def autocorrect(node)
+          lambda do |corrector|
+            corrector.replace(node, '::API::Base')
+          end
+        end
+      end
+    end
+  end
+end