[Fix rubocop#184] Fix Node#parent_module_name for sclass nodes.

changelog/fix_fix_184_fix_nodeparent_module_name_for.md

@@ -0,0 +1 @@
+* [#197](https://github.com/rubocop-hq/rubocop-ast/pull/197): [Fix #184] Fix `Node#parent_module_name` for `sclass` nodes. ([@dvandersluis][])

lib/rubocop/ast/node.rb

@@ -317,7 +317,11 @@ def parent_module_name
         # returns nil if answer cannot be determined
         ancestors = each_ancestor(:class, :module, :sclass, :casgn, :block)
         result    = ancestors.map do |ancestor|
-          parent_module_name_part(ancestor) { |full_name| return full_name }
+          parent_module_name_part(ancestor) do |full_name|
+            return nil unless full_name
+
+            full_name
+          end
         end.compact.reverse.join('::')
         result.empty? ? 'Object' : result
       end

spec/rubocop/ast/node_spec.rb

@@ -1,7 +1,7 @@
 # frozen_string_literal: true
 
 RSpec.describe RuboCop::AST::Node do
-  let(:ast) { RuboCop::AST::ProcessedSource.new(src, ruby_version).ast }
+  let(:ast) { parse_source(src).node }
   let(:node) { ast }
 
   describe '#value_used?' do
@@ -659,4 +659,86 @@ def variables; end
       end
     end
   end
+
+  describe '#parent_module_name' do
+    subject(:parent_module_name) { node.parent_module_name }
+
+    context 'when node on top level' do
+      let(:src) { 'def config; end' }
+
+      it { is_expected.to eq 'Object' }
+    end
+
+    context 'when node on module' do
+      let(:src) do
+        <<~RUBY
+          module Foo
+            >>attr_reader :config<<
+          end
+        RUBY
+      end
+
+      it { is_expected.to eq 'Foo' }
+    end
+
+    context 'when node on singleton class' do
+      let(:src) do
+        <<~RUBY
+          module Foo
+            class << self
+              >>attr_reader :config<<
+            end
+          end
+        RUBY
+      end
+
+      it { is_expected.to eq 'Foo::#<Class:Foo>' }
+    end
+
+    context 'when node on class in singleton class' do
+      let(:src) do
+        <<~RUBY
+          module Foo
+            class << self
+              class Bar
+                >>attr_reader :config<<
+              end
+            end
+          end
+        RUBY
+      end
+
+      it { is_expected.to eq 'Foo::#<Class:Foo>::Bar' }
+    end
+
+    context 'when node nested in an unknown block' do
+      let(:src) do
+        <<~RUBY
+          module Foo
+            foo do
+              class Bar
+                >>attr_reader :config<<
+              end
+            end
+          end
+        RUBY
+      end
+
+      it { is_expected.to eq nil }
+    end
+
+    context 'when node nested in a class << exp' do
+      let(:src) do
+        <<~RUBY
+          class A
+            class << expr
+              >>attr_reader :config<<
+            end
+          end
+        RUBY
+      end
+
+      it { is_expected.to eq nil }
+    end
+  end
 end