Don't assume first and last comments are aligned

changelog/fix_false_negative_for_layout_extra_spacing.md

@@ -0,0 +1 @@
+* [#12366](https://github.com/rubocop/rubocop/pull/12366): Fix a false negative for `Layout/ExtraSpacing` when a file has exactly two comments. ([@eugeneius][])

lib/rubocop/cop/layout/extra_spacing.rb

@@ -49,19 +49,13 @@ def on_new_investigation
 
         private
 
-        def aligned_locations(locs) # rubocop:disable Metrics/AbcSize
+        def aligned_locations(locs)
           return [] if locs.empty?
 
-          aligned = Set[locs.first.line, locs.last.line]
-          locs.each_cons(3) do |before, loc, after|
-            col = loc.column
-            aligned << loc.line if col == before.column || col == after.column
+          aligned = Set.new
+          locs.each_cons(2) do |loc1, loc2|
+            aligned << loc1.line << loc2.line if loc1.column == loc2.column
           end
-
-          # if locs.size > 2 and the size of variable `aligned`
-          # has not increased from its initial value, there are not aligned lines.
-          return [] if locs.size > 2 && aligned.size == 2
-
           aligned
         end
 

spec/rubocop/cop/layout/extra_spacing_spec.rb

@@ -604,6 +604,33 @@ def method(arg = 1)
     end
   end
 
+  context 'when exactly two comments have extra spaces' do
+    context 'and they are aligned' do
+      it 'does not register an offense' do
+        expect_no_offenses(<<~RUBY)
+          one  # comment one
+          two  # comment two
+        RUBY
+      end
+    end
+
+    context 'and they are not aligned' do
+      it 'registers an offense' do
+        expect_offense(<<~RUBY)
+          one  # comment one
+             ^ Unnecessary spacing detected.
+          two   # comment two
+             ^^ Unnecessary spacing detected.
+        RUBY
+
+        expect_correction(<<~RUBY)
+          one # comment one
+          two # comment two
+        RUBY
+      end
+    end
+  end
+
   context 'when multiple comments have extra spaces' do
     it 'registers offenses for all comments' do
       expect_offense(<<~RUBY)