[Fix #8506] Add AllowedParentClasses config to Lint/MissingSuper.

The default value of %w[BasicObject Object] is kept for backwards compatibility, but users can now add to that list using the AllowedParentClasses config value.

changelog/change_merge_pull_request_11936_from.md

@@ -0,0 +1 @@
+* [#8506](https://github.com/rubocop/rubocop/issues/8506): Add `AllowedParentClasses` config to `Lint/MissingSuper`. ([@iMacTia][])

config/default.yml

@@ -1988,6 +1988,7 @@ Lint/MissingSuper:
                   Checks for the presence of constructors and lifecycle callbacks
                   without calls to `super`.
   Enabled: true
+  AllowedParentClasses: []
   VersionAdded: '0.89'
   VersionChanged: '1.4'
 

lib/rubocop/cop/lint/missing_super.rb

@@ -14,6 +14,13 @@ module Lint
       # Autocorrection is not supported because the position of `super` cannot be
       # determined automatically.
       #
+      # `Object` and `BasicObject` are allowed by this cop because of their
+      # stateless nature. However, sometimes you might want to allow other parent
+      # classes from this cop, for example in the case of an abstract class that is
+      # not meant to be called with `super`. In those cases, you can use the
+      # `AllowedParentClasses` option to specify which classes should be allowed
+      # *in addition to* `Object` and `BasicObject`.
+      #
       # @example
       #   # bad
       #   class Employee < Person
@@ -60,6 +67,21 @@ module Lint
       #     end
       #   end
       #
+      #   # good
+      #   class ClassWithNoParent
+      #     def initialize
+      #       do_something
+      #     end
+      #   end
+      #
+      # @example AllowedParentClasses: [MyAbstractClass]
+      #   # good
+      #   class MyConcreteClass < MyAbstractClass
+      #     def initialize
+      #       do_something
+      #     end
+      #   end
+      #
       class MissingSuper < Base
         CONSTRUCTOR_MSG = 'Call `super` to initialize state of the parent class.'
         CALLBACK_MSG    = 'Call `super` to invoke callback defined in the parent class.'
@@ -116,16 +138,20 @@ def inside_class_with_stateful_parent?(node)
           if (block_node = node.each_ancestor(:block, :numblock).first)
             return false unless (super_class = class_new_block(block_node))
 
-            !stateless_class?(super_class)
+            !allowed_class?(super_class)
           elsif (class_node = node.each_ancestor(:class).first)
-            class_node.parent_class && !stateless_class?(class_node.parent_class)
+            class_node.parent_class && !allowed_class?(class_node.parent_class)
           else
             false
           end
         end
 
-        def stateless_class?(node)
-          STATELESS_CLASSES.include?(node.const_name)
+        def allowed_class?(node)
+          allowed_classes.include?(node.const_name)
+        end
+
+        def allowed_classes
+          @allowed_classes ||= STATELESS_CLASSES + cop_config.fetch('AllowedParentClasses', [])
         end
       end
     end

spec/rubocop/cop/lint/missing_super_spec.rb

@@ -207,4 +207,17 @@ def self.inherited(base)
       RUBY
     end
   end
+
+  context 'with custom AllowedParentClasses config' do
+    let(:cop_config) { { 'AllowedParentClasses' => %w[Array] } }
+
+    it 'does not register an offense for a class with custom stateless parent class' do
+      expect_no_offenses(<<~RUBY)
+        class Child < Array
+          def initialize
+          end
+        end
+      RUBY
+    end
+  end
 end