[Fix #159] Fix a false positive for Performance/AncestorsInclude

CHANGELOG.md

@@ -7,6 +7,10 @@
 * [#140](https://github.com/rubocop-hq/rubocop-performance/pull/140): Add new `Performance/CollectionLiteralInLoop` cop. ([@fatkodima][])
 * [#137](https://github.com/rubocop-hq/rubocop-performance/pull/137): Add new `Performance/Sum` cop. ([@fatkodima][])
 
+### Bug fixes
+
+* [#159](https://github.com/rubocop-hq/rubocop-performance/pull/159): Fix a false positive for `Performance/AncestorsInclude` when receiver is a variable. ([@koic][])
+
 ### Changes
 
 * [#154](https://github.com/rubocop-hq/rubocop-performance/pull/154): Require RuboCop 0.87 or higher. ([@koic][])

lib/rubocop/cop/performance/ancestors_include.rb

@@ -25,17 +25,23 @@ class AncestorsInclude < Base
 
         def on_send(node)
           return unless (subclass, superclass = ancestors_include_candidate?(node))
+          return if subclass && !subclass.const_type?
 
-          location_of_ancestors = node.children[0].loc.selector.begin_pos
-          end_location = node.loc.selector.end_pos
-          range = range_between(location_of_ancestors, end_location)
-
-          add_offense(range) do |corrector|
+          add_offense(range(node)) do |corrector|
             subclass_source = subclass ? subclass.source : 'self'
 
             corrector.replace(node, "#{subclass_source} <= #{superclass.source}")
           end
         end
+
+        private
+
+        def range(node)
+          location_of_ancestors = node.children[0].loc.selector.begin_pos
+          end_location = node.loc.selector.end_pos
+
+          range_between(location_of_ancestors, end_location)
+        end
       end
     end
   end

spec/rubocop/cop/performance/ancestors_include_spec.rb

@@ -25,6 +25,12 @@
     RUBY
   end
 
+  it 'does not register an offense when receiver is not a consntant' do
+    expect_no_offenses(<<~RUBY)
+      expect(object_one.ancestors.include?(object_two)).to eq(true)
+    RUBY
+  end
+
   it 'does not register an offense when using `<=`' do
     expect_no_offenses(<<~RUBY)
       Class <= Kernel