Fix #8820 autocorrection for Style/IfWithSemicolon

This change fixes autocorrection for Style/IfWithSemicolon when elsif present.

In case of one of more elsif conditions present, the autocorrector will create a full if, elsif, else structure.

CHANGELOG.md

@@ -5178,3 +5178,4 @@
 [@HeroProtagonist]: https://github.com/HeroProtagonist
 [@piotrmurach]: https://github.com/piotrmurach
 [@javierav]: https://github.com/javierav
+[@adrian-rivera]: https://github.com/adrian-rivera

changelog/fix_if_with_semicolon_correction.md

@@ -0,0 +1 @@
+* [#8820](https://github.com/rubocop-hq/rubocop/issues/8820): Fixes `IfWithSemicolon` autocorrection when `elsif` is present. ([@adrian-rivera][], [@dvandersluis][])

lib/rubocop/cop/style/if_with_semicolon.rb

@@ -17,26 +17,61 @@ class IfWithSemicolon < Base
         include OnNormalIfUnless
         extend AutoCorrector
 
-        MSG = 'Do not use if x; Use the ternary operator instead.'
+        MSG_IF_ELSE = 'Do not use `if %<expr>s;` - use `if/else` instead.'
+        MSG_TERNARY = 'Do not use `if %<expr>s;` - use a ternary operator instead.'
 
         def on_normal_if_unless(node)
           return unless node.else_branch
+          return if node.parent&.if_type?
 
           beginning = node.loc.begin
           return unless beginning&.is?(';')
 
-          add_offense(node) do |corrector|
-            corrector.replace(node, correct_to_ternary(node))
+          message = node.else_branch.if_type? ? MSG_IF_ELSE : MSG_TERNARY
+
+          add_offense(node, message: format(message, expr: node.condition.source)) do |corrector|
+            corrector.replace(node, autocorrect(node))
           end
         end
 
         private
 
-        def correct_to_ternary(node)
+        def autocorrect(node)
+          return correct_elsif(node) if node.else_branch.if_type?
+
           else_code = node.else_branch ? node.else_branch.source : 'nil'
 
           "#{node.condition.source} ? #{node.if_branch.source} : #{else_code}"
         end
+
+        def correct_elsif(node)
+          <<~RUBY.chop
+            if #{node.condition.source}
+              #{node.if_branch.source}
+            #{build_else_branch(node.else_branch).chop}
+            end
+          RUBY
+        end
+
+        def build_else_branch(second_condition)
+          result = <<~RUBY
+            elsif #{second_condition.condition.source}
+              #{second_condition.if_branch.source}
+          RUBY
+
+          if second_condition.else_branch
+            result += if second_condition.else_branch.if_type?
+                        build_else_branch(second_condition.else_branch)
+                      else
+                        <<~RUBY
+                          else
+                            #{second_condition.else_branch.source}
+                        RUBY
+                      end
+          end
+
+          result
+        end
       end
     end
   end

spec/rubocop/cop/style/if_with_semicolon_spec.rb

@@ -6,7 +6,7 @@
   it 'registers an offense and corrects for one line if/;/end' do
     expect_offense(<<~RUBY)
       if cond; run else dont end
-      ^^^^^^^^^^^^^^^^^^^^^^^^^^ Do not use if x; Use the ternary operator instead.
+      ^^^^^^^^^^^^^^^^^^^^^^^^^^ Do not use `if cond;` - use a ternary operator instead.
     RUBY
 
     expect_correction(<<~RUBY)
@@ -28,4 +28,57 @@ class Hash
       end if RUBY_VERSION < "1.8.7"
     RUBY
   end
+
+  context 'when elsif is present' do
+    it 'accepts without `else` branch' do
+      expect_offense(<<~RUBY)
+        if cond; run elsif cond2; run2 end
+        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Do not use `if cond;` - use `if/else` instead.
+      RUBY
+
+      expect_correction(<<~RUBY)
+        if cond
+          run
+        elsif cond2
+          run2
+        end
+      RUBY
+    end
+
+    it 'accepts second elsif block' do
+      expect_offense(<<~RUBY)
+        if cond; run elsif cond2; run2 elsif cond3; run3 else dont end
+        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Do not use `if cond;` - use `if/else` instead.
+      RUBY
+
+      expect_correction(<<~RUBY)
+        if cond
+          run
+        elsif cond2
+          run2
+        elsif cond3
+          run3
+        else
+          dont
+        end
+      RUBY
+    end
+
+    it 'accepts with `else` branch' do
+      expect_offense(<<~RUBY)
+        if cond; run elsif cond2; run2 else dont end
+        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Do not use `if cond;` - use `if/else` instead.
+      RUBY
+
+      expect_correction(<<~RUBY)
+        if cond
+          run
+        elsif cond2
+          run2
+        else
+          dont
+        end
+      RUBY
+    end
+  end
 end