[Fix #9731] Fix two autocorrection issues for `Style/NegatedIfElseCon…

…dition`.

Previously, when swapping the `if` and `else` branches, if one of the branches only had a single statement, the branch would end up not being spaced out properly.

Additionally, when there is a node with a comment inside the `if` that has an identical node with a comment *before* the `if` statement, `CommentsHelp.begin_pos_with_comment` returns an incorrect range, which was causing a clobbering error. I fixed this by creating ranges of the entire body of the if and else branches, so that they can just be swapped without relying on `ProcessedSource#ast_with_comments`.

changelog/fix_fix_two_autocorrection_issues_for.md

@@ -0,0 +1 @@
+* [#9731](https://github.com/rubocop/rubocop/issues/9731): Fix two autocorrection issues for `Style/NegatedIfElseCondition`. ([@dvandersluis][])

lib/rubocop/cop/style/negated_if_else_condition.rb

@@ -29,7 +29,6 @@ module Style
       #
       class NegatedIfElseCondition < Base
         include RangeHelp
-        include CommentsHelp
         extend AutoCorrector
 
         MSG = 'Invert the negated condition and swap the %<type>s branches.'
@@ -98,21 +97,30 @@ def swap_branches(corrector, node)
           if node.if_branch.nil?
             corrector.remove(range_by_whole_lines(node.loc.else, include_final_newline: true))
           else
-            if_range = node_with_comments(node.if_branch)
-            else_range = node_with_comments(node.else_branch)
+            if_range = if_range(node)
+            else_range = else_range(node)
 
             corrector.replace(if_range, else_range.source)
             corrector.replace(else_range, if_range.source)
           end
         end
 
-        def node_with_comments(node)
-          first_statement = node.begin_type? ? node.children[0] : node
-          return node if processed_source.ast_with_comments[first_statement].empty?
+        # Collect the entire if branch, including whitespace and comments
+        def if_range(node)
+          if node.ternary?
+            node.if_branch
+          else
+            range_between(node.condition.loc.expression.end_pos, node.loc.else.begin_pos)
+          end
+        end
 
-          begin_pos = source_range_with_comment(first_statement).begin_pos
-          end_pos = node.source_range.end_pos
-          Parser::Source::Range.new(buffer, begin_pos, end_pos)
+        # Collect the entire else branch, including whitespace and comments
+        def else_range(node)
+          if node.ternary?
+            node.else_branch
+          else
+            range_between(node.loc.else.end_pos, node.loc.end.begin_pos)
+          end
         end
       end
     end

spec/rubocop/cop/style/negated_if_else_condition_spec.rb

@@ -50,6 +50,21 @@
     RUBY
   end
 
+  it 'registers an offens and corrects a multiline ternary' do
+    expect_offense(<<~RUBY)
+      !x ?
+      ^^^^ Invert the negated condition and swap the ternary branches.
+        do_something :
+        do_something_else # comment
+    RUBY
+
+    expect_correction(<<~RUBY)
+      x ?
+        do_something_else :
+        do_something # comment
+    RUBY
+  end
+
   shared_examples 'negation method' do |method, inverted_method|
     it "registers an offense and corrects when negating condition with `#{method}` for `if-else`" do
       expect_offense(<<~RUBY, method: method)
@@ -129,6 +144,23 @@
     RUBY
   end
 
+  it 'does not register an offense when the `else` branch is empty' do
+    expect_no_offenses(<<~RUBY)
+      if !condition.nil?
+        foo = 42
+      else
+      end
+    RUBY
+  end
+
+  it 'does not register an offense when both branches are empty' do
+    expect_no_offenses(<<~RUBY)
+      if !condition.nil?
+      else
+      end
+    RUBY
+  end
+
   it 'moves comments to correct branches during autocorrect' do
     expect_offense(<<~RUBY)
       if !condition.nil?
@@ -187,6 +219,98 @@
     RUBY
   end
 
+  it 'works with comments when one branch is a begin and the other is not' do
+    expect_offense(<<~RUBY)
+      if !condition
+      ^^^^^^^^^^^^^ Invert the negated condition and swap the if-else branches.
+        # comment
+        do_a
+        do_b
+      else
+        do_c
+      end
+    RUBY
+
+    expect_correction(<<~RUBY)
+      if condition
+        do_c
+      else
+        # comment
+        do_a
+        do_b
+      end
+    RUBY
+  end
+
+  it 'works with comments when neither branch is a begin node' do
+    expect_offense(<<~RUBY)
+      if !condition
+      ^^^^^^^^^^^^^ Invert the negated condition and swap the if-else branches.
+        # comment
+        do_b
+      else
+        do_c
+      end
+    RUBY
+
+    expect_correction(<<~RUBY)
+      if condition
+        do_c
+      else
+        # comment
+        do_b
+      end
+    RUBY
+  end
+
+  it 'works with duplicate nodes' do
+    expect_offense(<<~RUBY)
+      # outer comment
+      do_a
+
+      if !condition
+      ^^^^^^^^^^^^^ Invert the negated condition and swap the if-else branches.
+        # comment
+        do_a
+      else
+        do_c
+      end
+    RUBY
+
+    expect_correction(<<~RUBY)
+      # outer comment
+      do_a
+
+      if condition
+        do_c
+      else
+        # comment
+        do_a
+      end
+    RUBY
+  end
+
+  it 'correctly moves comments at the end of branches' do
+    expect_offense(<<~RUBY)
+      if !condition
+      ^^^^^^^^^^^^^ Invert the negated condition and swap the if-else branches.
+        do_a
+        # comment
+      else
+        do_c
+      end
+    RUBY
+
+    expect_correction(<<~RUBY)
+      if condition
+        do_c
+      else
+        do_a
+        # comment
+      end
+    RUBY
+  end
+
   it 'does not register an offense when negating condition for `if-elsif`' do
     expect_no_offenses(<<~RUBY)
       if !x