[Fix #5022] Fix false negative for Lint/DuplicateMethods inside `cl…

…ass << self`.

lib/rubocop/cop/lint/duplicate_methods.rb

@@ -135,11 +135,14 @@ def message_for_dup(node, method_name)
         def found_instance_method(node, name)
           return unless (scope = node.parent_module_name)
 
-          if scope =~ /\A#<Class:(.*)>\Z/
-            found_method(node, "#{Regexp.last_match(1)}.#{name}")
-          else
-            found_method(node, "#{scope}##{name}")
-          end
+          # Humanize the scope
+          scope = scope.sub(
+            /(?:(?<name>.*)::)#<Class:\k<name>>|#<Class:(?<name>.*)>(?:::)?/,
+            '\k<name>.'
+          )
+          scope << '#' unless scope.end_with?('.')
+
+          found_method(node, "#{scope}#{name}")
         end
 
         def found_method(node, method_name)

rubocop.gemspec

@@ -35,7 +35,7 @@ Gem::Specification.new do |s|
   s.add_runtime_dependency('rainbow', '>= 2.2.2', '< 4.0')
   s.add_runtime_dependency('regexp_parser', '>= 1.8', '< 3.0')
   s.add_runtime_dependency('rexml')
-  s.add_runtime_dependency('rubocop-ast', '>= 1.9.0', '< 2.0')
+  s.add_runtime_dependency('rubocop-ast', '>= 1.9.1', '< 2.0')
   s.add_runtime_dependency('ruby-progressbar', '~> 1.7')
   s.add_runtime_dependency('unicode-display_width', '>= 1.4.0', '< 3.0')
 

spec/rubocop/cop/lint/duplicate_methods_spec.rb

@@ -196,7 +196,7 @@ def some_method
       RUBY
     end
 
-    xit 'understands class << self' do
+    it 'understands class << self' do
       expect_offense(<<~RUBY, 'test.rb')
         #{opening_line}
           class << self
@@ -424,8 +424,8 @@ def A.some_method
       RUBY
     end
 
-    xit 'registers an offense for duplicate class methods with `<<` and named ' \
-        "receiver in #{type}" do
+    it 'registers an offense for duplicate class methods with `<<` and named ' \
+       "receiver in #{type}" do
       expect_offense(<<~RUBY, 'test.rb')
         #{type} A
           class << self
@@ -510,6 +510,41 @@ def foo
     RUBY
   end
 
+  it 'does not register for the same method in different scopes within `class << self`' do
+    expect_no_offenses(<<~RUBY, 'test.rb')
+      class A
+        class << self
+          def foo
+          end
+
+          class B
+            def foo
+            end
+          end
+        end
+      end
+    RUBY
+  end
+
+  it 'properly registers and offense when deeply nested' do
+    expect_offense(<<~RUBY, 'test.rb')
+      module A
+        module B
+          class C
+            class << self
+              def foo
+              end
+
+              def foo
+              ^^^^^^^ Method `A::B::C.foo` is defined at both test.rb:5 and test.rb:8.
+              end
+            end
+          end
+        end
+      end
+    RUBY
+  end
+
   context 'when path is in the project root' do
     before do
       allow(Dir).to receive(:pwd).and_return('/path/to/project/root')