Add autocorrection to Lint/EmptyConditionalBody.

changelog/change_add_autocorrection_to.md

@@ -0,0 +1 @@
+* [#10862](https://github.com/rubocop/rubocop/pull/10862): Add autocorrection to `Lint/EmptyConditionalBody`. ([@dvandersluis][])

config/default.yml

@@ -1755,6 +1755,7 @@ Lint/EmptyConditionalBody:
   Enabled: true
   AllowComments: true
   VersionAdded: '0.89'
+  VersionChanged: '<<next>>'
 
 Lint/EmptyEnsure:
   Description: 'Checks for empty ensure block.'

lib/rubocop/cop/lint/empty_conditional_body.rb

@@ -4,6 +4,9 @@ module RuboCop
   module Cop
     module Lint
       # Checks for the presence of `if`, `elsif` and `unless` branches without a body.
+      #
+      # NOTE: empty `else` branches are handled by `Style/EmptyElse`.
+      #
       # @example
       #   # bad
       #   if condition
@@ -53,15 +56,71 @@ module Lint
       #   end
       #
       class EmptyConditionalBody < Base
+        extend AutoCorrector
         include CommentsHelp
+        include RangeHelp
 
         MSG = 'Avoid `%<keyword>s` branches without a body.'
 
         def on_if(node)
           return if node.body
           return if cop_config['AllowComments'] && contains_comments?(node)
 
-          add_offense(node, message: format(MSG, keyword: node.keyword))
+          add_offense(node, message: format(MSG, keyword: node.keyword)) do |corrector|
+            autocorrect(corrector, node)
+          end
+        end
+
+        private
+
+        def autocorrect(corrector, node)
+          remove_comments(corrector, node)
+          remove_empty_branch(corrector, node)
+          correct_other_branches(corrector, node)
+        end
+
+        def remove_comments(corrector, node)
+          comments_in_range(node).each do |comment|
+            range = range_by_whole_lines(comment.loc.expression, include_final_newline: true)
+            corrector.remove(range)
+          end
+        end
+
+        def remove_empty_branch(corrector, node)
+          corrector.remove(deletion_range(branch_range(node)))
+        end
+
+        def correct_other_branches(corrector, node)
+          return unless (node.if? || node.unless?) && node.else_branch
+
+          if node.else_branch.if_type?
+            # Replace an orphaned `elsif` with `if`
+            corrector.replace(node.else_branch.loc.keyword, 'if')
+          else
+            # Flip orphaned `else`
+            corrector.replace(node.loc.else, "#{node.inverse_keyword} #{node.condition.source}")
+          end
+        end
+
+        def branch_range(node)
+          if node.loc.else
+            node.source_range.with(end_pos: node.loc.else.begin_pos - 1)
+          else
+            node.source_range
+          end
+        end
+
+        def deletion_range(range)
+          # Collect a range between the start of the `if` node and the next relevant node,
+          # including final new line.
+          # Based on `RangeHelp#range_by_whole_lines` but allows the `if` to not start
+          # on the first column.
+          buffer = @processed_source.buffer
+
+          last_line = buffer.source_line(range.last_line)
+          end_offset = last_line.length - range.last_column + 1
+
+          range.adjust(end_pos: end_offset).intersect(buffer.source_range)
         end
       end
     end

lib/rubocop/cop/mixin/comments_help.rb

@@ -12,10 +12,14 @@ def source_range_with_comment(node)
       end
 
       def contains_comments?(node)
+        comments_in_range(node).any?
+      end
+
+      def comments_in_range(node)
         start_line = node.source_range.line
         end_line = find_end_line(node)
 
-        processed_source.each_comment_in_lines(start_line...end_line).any?
+        processed_source.each_comment_in_lines(start_line...end_line)
       end
 
       private

spec/rubocop/cop/lint/empty_conditional_body_spec.rb

@@ -9,6 +9,8 @@
       ^^^^^^^^^^^^ Avoid `if` branches without a body.
       end
     RUBY
+
+    expect_correction('')
   end
 
   it 'does not register an offense for missing `if` body with a comment' do
@@ -27,6 +29,64 @@
       ^^^^^^^^^^^^^^^^^^^^^ Avoid `elsif` branches without a body.
       end
     RUBY
+
+    expect_correction(<<~RUBY)
+      if condition
+        do_something
+      end
+    RUBY
+  end
+
+  it 'registers an offense for missing `if` body with `else`' do
+    expect_offense(<<~RUBY)
+      if condition
+      ^^^^^^^^^^^^ Avoid `if` branches without a body.
+      else
+        do_something
+      end
+    RUBY
+
+    expect_correction(<<~RUBY)
+      unless condition
+        do_something
+      end
+    RUBY
+  end
+
+  it 'registers an offense for missing `unless` body with `else`' do
+    expect_offense(<<~RUBY)
+      unless condition
+      ^^^^^^^^^^^^^^^^ Avoid `unless` branches without a body.
+      else
+        do_something
+      end
+    RUBY
+
+    expect_correction(<<~RUBY)
+      if condition
+        do_something
+      end
+    RUBY
+  end
+
+  it 'registers an offense for missing `if` body with `elsif`' do
+    expect_offense(<<~RUBY)
+      if condition
+      ^^^^^^^^^^^^ Avoid `if` branches without a body.
+      elsif other_condition
+        do_something
+      elsif another_condition
+        do_something_else
+      end
+    RUBY
+
+    expect_correction(<<~RUBY)
+      if other_condition
+        do_something
+      elsif another_condition
+        do_something_else
+      end
+    RUBY
   end
 
   it 'does not register an offense for missing `elsif` body with a comment' do
@@ -49,6 +109,14 @@
         # noop
       end
     RUBY
+
+    expect_correction(<<~RUBY)
+      if condition
+        do_something
+      else
+        # noop
+      end
+    RUBY
   end
 
   it 'does not register an offense for missing `elsif` body with an inline comment' do
@@ -72,6 +140,14 @@
       ^^^^^^^^^ Avoid `elsif` branches without a body.
       end
     RUBY
+
+    expect_correction(<<~RUBY)
+      if foo
+        do_foo
+      elsif bar
+        do_bar
+      end
+    RUBY
   end
 
   it 'registers an offense for missing `unless` body' do
@@ -80,6 +156,8 @@
       ^^^^^^^^^^^^^^^^ Avoid `unless` branches without a body.
       end
     RUBY
+
+    expect_correction('')
   end
 
   it 'does not register an offense for missing `unless` body with a comment' do
@@ -90,6 +168,22 @@
     RUBY
   end
 
+  it 'autocorrects properly when the if is assigned to a variable' do
+    expect_offense(<<~RUBY)
+      x = if foo
+          ^^^^^^ Avoid `if` branches without a body.
+      elsif bar
+        5
+      end
+    RUBY
+
+    expect_correction(<<~RUBY)
+      x = if bar
+        5
+      end
+    RUBY
+  end
+
   context 'when AllowComments is false' do
     let(:cop_config) { { 'AllowComments' => false } }
 
@@ -100,6 +194,8 @@
           # noop
         end
       RUBY
+
+      expect_correction('')
     end
 
     it 'registers an offense for missing `elsif` body with a comment' do
@@ -111,6 +207,12 @@
           # noop
         end
       RUBY
+
+      expect_correction(<<~RUBY)
+        if condition
+          do_something
+        end
+      RUBY
     end
 
     it 'registers an offense for missing `unless` body with a comment' do
@@ -120,6 +222,8 @@
           # noop
         end
       RUBY
+
+      expect_correction('')
     end
   end
 end