Only report FeatureEnvy for instance methods

lib/reek/smell_detectors/feature_envy.rb

@@ -43,6 +43,7 @@ class FeatureEnvy < BaseDetector
       # @return [Array<SmellWarning>]
       #
       def sniff
+        return [] if context.singleton_method? || context.module_function?
         return [] unless context.references_self?
         envious_receivers.map do |name, lines|
           smell_warning(

spec/reek/smell_detectors/feature_envy_spec.rb

@@ -247,4 +247,49 @@ def alfa(bravo)
 
     expect(src).not_to reek_of(:FeatureEnvy)
   end
+
+  it 'does not report on class methods defined by opening the metaclass' do
+    src = <<-EOS
+      class Alfa
+        class << self
+          def bravo(charlie)
+            delta = new(charlie)
+            delta.echo
+            delta.echo
+          end
+        end
+      end
+    EOS
+
+    expect(src).not_to reek_of(:FeatureEnvy)
+  end
+
+  it 'does not report on class methods defined with an explicit receiver' do
+    src = <<-EOS
+      class Alfa
+        def self.bravo(charlie)
+          delta = new(charlie)
+          delta.echo
+          delta.echo
+        end
+      end
+    EOS
+
+    expect(src).not_to reek_of(:FeatureEnvy)
+  end
+
+  it 'does not report module functions' do
+    src = <<-EOF
+      module Alfa
+        module_function
+        def bravo(charlie)
+          echo = delta(charlie)
+          echo.foxtrot
+          echo.foxtrot
+        end
+      end
+    EOF
+
+    expect(src).not_to reek_of(:FeatureEnvy)
+  end
 end