[#8489](#8489) Exclude method respond_to_missing? from OptionalBoolea…

…nParameter cop.

CHANGELOG.md

@@ -54,6 +54,7 @@
 * [#8629](https://github.com/rubocop-hq/rubocop/pull/8629): Fix the cache being reusable in CI by using crc32 to calculate file hashes rather than `mtime`, which changes each CI build. ([@dvandersluis][])
 * [#8663](https://github.com/rubocop-hq/rubocop/issues/8663): Fix multiple autocorrection bugs with `Style/ClassMethodsDefinitions`. ([@dvandersluis][])
 * [#8621](https://github.com/rubocop-hq/rubocop/issues/8621): Add helpful Infinite Loop error message. ([@iSarCasm][])
+* [#8489](https://github.com/rubocop-hq/rubocop/issues/8489):  Exclude method `respond_to_missing?` from `OptionalBooleanParameter` cop. ([@em-gazelle][])
 
 ## 0.90.0 (2020-09-01)
 
@@ -4881,3 +4882,4 @@
 [@sascha-wolf]: https://github.com/sascha-wolf
 [@fsateler]: https://github.com/fsateler
 [@iSarCasm]: https://github.com/iSarCasm
+[@em-gazelle]: https://github.com/em-gazelle

lib/rubocop/cop/style/optional_boolean_parameter.rb

@@ -26,8 +26,11 @@ module Style
       class OptionalBooleanParameter < Base
         MSG = 'Use keyword arguments when defining method with boolean argument.'
         BOOLEAN_TYPES = %i[true false].freeze
+        METHODS_EXCLUDED = %i[respond_to_missing?].freeze
 
         def on_def(node)
+          return if METHODS_EXCLUDED.include?(node.method_name)
+
           node.arguments.each do |arg|
             next unless arg.optarg_type?
 

spec/rubocop/cop/style/optional_boolean_parameter_spec.rb

@@ -42,10 +42,17 @@ def some_method
     RUBY
   end
 
-  it 'does not register an offense when defining method with optonal non-boolean arg' do
+  it 'does not register an offense when defining method with optional non-boolean arg' do
     expect_no_offenses(<<~RUBY)
       def some_method(bar = 'foo')
       end
     RUBY
   end
+
+  it 'does not register an offense when defining respond_to_missing? method with boolean arg' do
+    expect_no_offenses(<<~RUBY)
+      def respond_to_missing?(arg, bar = false)
+      end
+    RUBY
+  end
 end