[Fix rubocop#2912]Fix ForceEqualSignAlignment check

We should check whether a line is aligned with the following line if the preceding line is not an assignment statement.

This fixes rubocop#2912

CHANGELOG.md

@@ -33,6 +33,7 @@
 * [#3039](https://github.com/bbatsov/rubocop/issues/3039): Accept `match` without a receiver in `Performance/EndWith`. ([@lumeet][])
 * [#3039](https://github.com/bbatsov/rubocop/issues/3039): Accept `match` without a receiver in `Performance/StartWith`. ([@lumeet][])
 * [#3048](https://github.com/bbatsov/rubocop/issues/3048): `Lint/NestedMethodDefinition` shouldn't flag methods defined on Structs. ([@owst][])
+* [#2912](https://github.com/bbatsov/rubocop/issues/2912): Check whether a line is aligned with the following line if the preceding line is not an assignment. ([@akihiro17][])
 
 ### Changes
 
@@ -2126,3 +2127,4 @@
 [@bolshakov]: https://github.com/bolshakov
 [@jastkand]: https://github.com/jastkand
 [@graemeboy]: https://github.com/graemeboy
+[@akihiro17]: https://github.com/akihiro17

lib/rubocop/cop/style/extra_spacing.rb

@@ -67,16 +67,31 @@ def check_tokens(ast, t1, t2)
         end
 
         def check_assignment(token)
-          # minus 2 is because pos.line is zero-based
-          line = processed_source.lines[token.pos.line - 2]
-          return if aligned_assignment?(token.pos, line)
-
-          preceding  = @asgn_lines.include?(token.pos.line - 1)
-          align_with = preceding ? 'preceding' : 'following'
-          message    = format(MSG_UNALIGNED_ASGN, align_with)
+          assignment_line = ''
+          message = ''
+          if should_aligned_with_preceding_line?(token)
+            assignment_line = preceding_line(token)
+            message = format(MSG_UNALIGNED_ASGN, 'preceding')
+          else
+            assignment_line = following_line(token)
+            message = format(MSG_UNALIGNED_ASGN, 'following')
+          end
+          return if aligned_assignment?(token.pos, assignment_line)
           add_offense(token.pos, token.pos, message)
         end
 
+        def should_aligned_with_preceding_line?(token)
+          @asgn_lines.include?(token.pos.line - 1)
+        end
+
+        def preceding_line(token)
+          processed_source.lines[token.pos.line - 2]
+        end
+
+        def following_line(token)
+          processed_source.lines[token.pos.line]
+        end
+
         def check_other(t1, t2, ast)
           return if t1.pos.line != t2.pos.line
           return if t2.pos.begin_pos - 1 <= t1.pos.end_pos

spec/rubocop/cop/style/extra_spacing_spec.rb

@@ -253,6 +253,13 @@
       expect(cop.offenses.size).to eq(0)
     end
 
+    it 'aligns the first assignment with the following assingment' do
+      inspect_source(cop, ['# comment',
+                           'a   = 1',
+                           'bb  = 2'])
+      expect(cop.offenses.size).to eq(0)
+    end
+
     it 'autocorrects consecutive assignments which are not aligned' do
       new_source = autocorrect_source(cop, ['a = 1',
                                             'bb = 2',