[Fix #10586] Fix a false positive for Style/DoubleNegation

changelog/fix_a_false_positive_double_negation.md

@@ -0,0 +1 @@
+* [#10586](https://github.com/rubocop/rubocop/issues/10586): Fix a false positive for `Style/DoubleNegation` when using `define_method` or `define_singleton_method`. ([@ydah][])

lib/rubocop/cop/style/double_negation.rb

@@ -37,11 +37,27 @@ module Style
       #     !!return_value
       #   end
       #
+      #   define_method :foo? do
+      #     !!return_value
+      #   end
+      #
+      #   define_singleton_method :foo? do
+      #     !!return_value
+      #   end
+      #
       # @example EnforcedStyle: forbidden
       #   # bad
       #   def foo?
       #     !!return_value
       #   end
+      #
+      #   define_method :foo? do
+      #     !!return_value
+      #   end
+      #
+      #   define_singleton_method :foo? do
+      #     !!return_value
+      #   end
       class DoubleNegation < Base
         include ConfigurableEnforcedStyle
         extend AutoCorrector
@@ -73,22 +89,32 @@ def end_of_method_definition?(node)
           return false unless (def_node = find_def_node_from_ascendant(node))
 
           conditional_node = find_conditional_node_from_ascendant(node)
-          last_child = find_last_child(def_node.body)
+          last_child = find_last_child(def_node.send_type? ? def_node : def_node.body)
 
           if conditional_node
             double_negative_condition_return_value?(node, last_child, conditional_node)
           else
-            last_child.last_line == node.last_line
+            last_child.last_line <= node.last_line
           end
         end
 
         def find_def_node_from_ascendant(node)
           return unless (parent = node.parent)
           return parent if parent.def_type? || parent.defs_type?
+          return node.parent.child_nodes.first if define_mehod?(parent)
 
           find_def_node_from_ascendant(node.parent)
         end
 
+        def define_mehod?(node)
+          return false unless node.block_type?
+
+          child = node.child_nodes.first
+          return false unless child.send_type?
+
+          child.method?(:define_method) || child.method?(:define_singleton_method)
+        end
+
         def find_conditional_node_from_ascendant(node)
           return unless (parent = node.parent)
           return parent if parent.conditional?

spec/rubocop/cop/style/double_negation_spec.rb

@@ -352,6 +352,24 @@ def foo?
       RUBY
     end
 
+    it 'does not register an offense for `!!` when return location by `define_method`' do
+      expect_no_offenses(<<~RUBY)
+        define_method :foo? do
+          bar
+          !!qux
+        end
+      RUBY
+    end
+
+    it 'does not register an offense for `!!` when return location by `define_singleton_method`' do
+      expect_no_offenses(<<~RUBY)
+        define_singleton_method :foo? do
+          bar
+          !!qux
+        end
+      RUBY
+    end
+
     it 'does not register an offense for `!!` when return location and using `rescue`' do
       expect_no_offenses(<<~RUBY)
         def foo?