[Fix rubocop#10010] Fix a false positive for Style/DoubleNegation

Fixes rubocop#10010.

This PR fixes a false positive for `Style/DoubleNegation`
when `!!` is used at return location and before `rescue` keyword.

changelog/fix_false_positive_for_style_double_negation.md

@@ -0,0 +1 @@
+* [#10010](https://github.com/rubocop/rubocop/issues/10010): Fix a false positive for `Style/DoubleNegation` when `!!` is used at return location and before `rescue` keyword. ([@koic][])

lib/rubocop/cop/style/double_negation.rb

@@ -62,7 +62,7 @@ def allowed_in_returns?(node)
         def end_of_method_definition?(node)
           return false unless (def_node = find_def_node_from_ascendant(node))
 
-          last_child = def_node.child_nodes.last
+          last_child = find_last_child(def_node.body)
 
           last_child.last_line == node.last_line
         end
@@ -73,6 +73,17 @@ def find_def_node_from_ascendant(node)
 
           find_def_node_from_ascendant(node.parent)
         end
+
+        def find_last_child(node)
+          case node.type
+          when :rescue
+            find_last_child(node.body)
+          when :ensure
+            find_last_child(node.child_nodes.first)
+          else
+            node.child_nodes.last
+          end
+        end
       end
     end
   end

spec/rubocop/cop/style/double_negation_spec.rb

@@ -66,6 +66,56 @@ def foo?
         end
       RUBY
     end
+
+    it 'does not register an offense for `!!` when return location and using `rescue`' do
+      expect_no_offenses(<<~RUBY)
+        def foo?
+          bar
+          !!baz.do_something
+        rescue
+          qux
+        end
+      RUBY
+    end
+
+    it 'does not register an offense for `!!` when return location and using `ensure`' do
+      expect_no_offenses(<<~RUBY)
+        def foo?
+          bar
+          !!baz.do_something
+        ensure
+          qux
+        end
+      RUBY
+    end
+
+    it 'does not register an offense for `!!` when return location and using `rescue` and `ensure`' do
+      expect_no_offenses(<<~RUBY)
+        def foo?
+          bar
+          !!baz.do_something
+        rescue
+          qux
+        ensure
+          corge
+        end
+      RUBY
+    end
+
+    it 'does not register an offense for `!!` when return location and using `rescue`, `else`, and `ensure`' do
+      expect_no_offenses(<<~RUBY)
+        def foo?
+          bar
+          !!baz.do_something
+        rescue
+          qux
+        else
+          quux
+        ensure
+          corge
+        end
+      RUBY
+    end
   end
 
   context 'when `EnforcedStyle: forbidden`' do
@@ -109,5 +159,101 @@ def foo?
         end
       RUBY
     end
+
+    it 'registers an offense for `!!` when return location and using `rescue`' do
+      expect_offense(<<~RUBY)
+        def foo?
+          bar
+          !!baz.do_something
+          ^ Avoid the use of double negation (`!!`).
+        rescue
+          qux
+        end
+      RUBY
+
+      expect_correction(<<~RUBY)
+        def foo?
+          bar
+          !baz.do_something.nil?
+        rescue
+          qux
+        end
+      RUBY
+    end
+
+    it 'registers an offense for `!!` when return location and using `ensure`' do
+      expect_offense(<<~RUBY)
+        def foo?
+          bar
+          !!baz.do_something
+          ^ Avoid the use of double negation (`!!`).
+        ensure
+          qux
+        end
+      RUBY
+
+      expect_correction(<<~RUBY)
+        def foo?
+          bar
+          !baz.do_something.nil?
+        ensure
+          qux
+        end
+      RUBY
+    end
+
+    it 'registers an offense for `!!` when return location and using `rescue` and `ensure`' do
+      expect_offense(<<~RUBY)
+        def foo?
+          bar
+          !!baz.do_something
+          ^ Avoid the use of double negation (`!!`).
+        rescue
+          baz
+        ensure
+          qux
+        end
+      RUBY
+
+      expect_correction(<<~RUBY)
+        def foo?
+          bar
+          !baz.do_something.nil?
+        rescue
+          baz
+        ensure
+          qux
+        end
+      RUBY
+    end
+
+    it 'registers an offense for `!!` when return location and using `rescue`, `else`, and `ensure`' do
+      expect_offense(<<~RUBY)
+        def foo?
+          bar
+          !!baz.do_something
+          ^ Avoid the use of double negation (`!!`).
+        rescue
+          qux
+        else
+          quux
+        ensure
+          corge
+        end
+      RUBY
+
+      expect_correction(<<~RUBY)
+        def foo?
+          bar
+          !baz.do_something.nil?
+        rescue
+          qux
+        else
+          quux
+        ensure
+          corge
+        end
+      RUBY
+    end
   end
 end