[Fix #10130] Update Lint/ElseLayout to be able to handle an else with only a single line

changelog/change_update_lintelselayout_to_be_able_to.md

@@ -0,0 +1 @@
+* [#10130](https://github.com/rubocop/rubocop/issues/10130): Update `Lint/ElseLayout` to be able to handle an `else` with only a single line. ([@dvandersluis][])

lib/rubocop/cop/lint/else_layout.rb

@@ -49,6 +49,9 @@ class ElseLayout < Base
         def on_if(node)
           return if node.ternary?
 
+          # If the if is on a single line, it'll be handled by `Style/OneLineConditional`
+          return if node.single_line?
+
           check(node)
         end
 
@@ -66,10 +69,7 @@ def check(node)
 
         def check_else(node)
           else_branch = node.else_branch
-
-          return unless else_branch.begin_type?
-
-          first_else = else_branch.children.first
+          first_else = else_branch.begin_type? ? else_branch.children.first : else_branch
 
           return unless first_else
           return unless first_else.source_range.line == node.loc.else.line
@@ -81,9 +81,13 @@ def autocorrect(corrector, node, first_else)
           corrector.insert_after(node.loc.else, "\n")
 
           blank_range = range_between(node.loc.else.end_pos, first_else.loc.expression.begin_pos)
-          indentation = indent(node.else_branch.children[1])
+          indentation = indent(node, offset: indentation_width)
           corrector.replace(blank_range, indentation)
         end
+
+        def indentation_width
+          @config.for_cop('Layout/IndentationWidth')['Width'] || 2
+        end
       end
     end
   end

lib/rubocop/cop/util.rb

@@ -129,8 +129,8 @@ def same_line?(node1, node2)
         node1.respond_to?(:loc) && node2.respond_to?(:loc) && node1.loc.line == node2.loc.line
       end
 
-      def indent(node)
-        ' ' * node.loc.column
+      def indent(node, offset: 0)
+        ' ' * (node.loc.column + offset)
       end
 
       def to_supported_styles(enforced_style)

spec/rubocop/cop/lint/else_layout_spec.rb

@@ -23,22 +23,31 @@
     RUBY
   end
 
-  it 'accepts proper else' do
-    expect_no_offenses(<<~RUBY)
+  it 'registers an offense and corrects for the entire else body being on the same line' do
+    expect_offense(<<~RUBY)
       if something
         test
-      else
-        something
+      else something_else
+           ^^^^^^^^^^^^^^ Odd `else` layout detected. Did you mean to use `elsif`?
+      end
+    RUBY
+
+    expect_correction(<<~RUBY)
+      if something
         test
+      else
+        something_else
       end
     RUBY
   end
 
-  it 'accepts single-expr else regardless of layout' do
+  it 'accepts proper else' do
     expect_no_offenses(<<~RUBY)
       if something
         test
-      else bala
+      else
+        something
+        test
       end
     RUBY
   end
@@ -116,4 +125,19 @@
       end
     RUBY
   end
+
+  it 'does not register an offense for an elsif with no body' do
+    expect_no_offenses(<<~RUBY)
+      if something
+        foo
+      elsif something_else
+      end
+    RUBY
+  end
+
+  it 'does not register an offense if the entire if is on a single line' do
+    expect_no_offenses(<<~RUBY)
+      if a then b else c end
+    RUBY
+  end
 end