[Fix rubocop#10090] Fix a false negative for Style/ArgumentsForwarding

Fixes rubocop#10090.

This PR fixes a false negative for `Style/ArgumentsForwarding`
when using only kwrest arg.

changelog/fix_false_negative_for_style_arguments_forwarding.md

@@ -0,0 +1 @@
+* [#10090](https://github.com/rubocop/rubocop/issues/10090): Fix a false negative for `Style/ArgumentsForwarding` when using only kwrest arg. ([@koic][])

lib/rubocop/cop/style/arguments_forwarding.rb

@@ -30,6 +30,10 @@ module Style
       #     bar(*args)
       #   end
       #
+      #   def foo(**kwargs)
+      #     bar(**kwargs)
+      #   end
+      #
       # @example AllowOnlyRestArgument: false
       #   # bad
       #   # The following code can replace the arguments with `...`,
@@ -38,6 +42,10 @@ module Style
       #     bar(*args)
       #   end
       #
+      #   def foo(**kwargs)
+      #     bar(**kwargs)
+      #   end
+      #
       class ArgumentsForwarding < Base
         include RangeHelp
         extend AutoCorrector
@@ -49,12 +57,15 @@ class ArgumentsForwarding < Base
 
         # @!method use_rest_arguments?(node)
         def_node_matcher :use_rest_arguments?, <<~PATTERN
-          (args (restarg $_) $...)
+          (args ({restarg kwrestarg} $_) $...)
         PATTERN
 
         # @!method only_rest_arguments?(node, name)
         def_node_matcher :only_rest_arguments?, <<~PATTERN
-          (send _ _ (splat (lvar %1)))
+          {
+            (send _ _ (splat (lvar %1)))
+            (send _ _ (hash (kwsplat (lvar %1))))
+          }
         PATTERN
 
         # @!method forwarding_method_arguments?(node, rest_name, block_name, kwargs_name)

spec/rubocop/cop/style/arguments_forwarding_spec.rb

@@ -204,6 +204,14 @@ def foo(*args)
           end
         RUBY
       end
+
+      it 'does not register an offense when using only kwrest arg' do
+        expect_no_offenses(<<~RUBY)
+          def foo(**kwargs)
+            bar(**kwargs)
+          end
+        RUBY
+      end
     end
 
     context 'AllowOnlyRestArgument: false' do
@@ -224,6 +232,22 @@ def foo(...)
           end
         RUBY
       end
+
+      it 'registers an offense when using only kwrest arg' do
+        expect_offense(<<~RUBY)
+          def foo(**kwargs)
+                  ^^^^^^^^ Use arguments forwarding.
+            bar(**kwargs)
+                ^^^^^^^^ Use arguments forwarding.
+          end
+        RUBY
+
+        expect_correction(<<~RUBY)
+          def foo(...)
+            bar(...)
+          end
+        RUBY
+      end
     end
   end
 end