[Fix #6566] Fix a false positive for `Layout/EmptyLinesAroundAccessMo…

…difier`

Fixes #6566.

This PR fixes a false positive for `Layout/EmptyLinesAroundAccessModifier`
when at the end of specifying a superclass is missing blank line.

The following is originally no offense code.
(It is probably a regression by #6307)

```console
% cat example.rb
class SomeController < SomeOtherController
  def index; end

  private
end

% rubocop example.rb --only Layout/EmptyLinesAroundAccessModifier -a
Inspecting 1 file
C

Offenses:

example.rb:4:3: C: [Corrected] Layout/EmptyLinesAroundAccessModifier:
Keep a blank line before and after private.
  private
  ^^^^^^^

1 file inspected, 1 offense detected, 1 offense corrected
```

Auto-correct adds a blank line after `private`. This is due to false positives.

```diff
 % cat example.rb
 class SomeController < SomeOtherController
   def index; end

   private
+
 end
```

This caused the infinite loop in `Layout/EmptyLinesAroundAccessModifier` and
`Layout/EmptyLinesAroundClassBody`.

```console
% rubocop example.rb --only Layout/EmptyLinesAroundClassBody -a
Inspecting 1 file
C

Offenses:

example.rb:5:1: C: [Corrected] Layout/EmptyLinesAroundClassBody: Extra
empty line detected at class body end.

1 file inspected, 1 offense detected, 1 offense corrected
```

Auto-correct removes the blank line from after of `private`.

```diff
 % cat example.rb
 class SomeController < SomeOtherController
   def index; end

   private
-
 end
```

It loops to the first code. This PR fixes the infinite loop.

CHANGELOG.md

@@ -7,6 +7,7 @@
 * [#6554](https://github.com/rubocop-hq/rubocop/issues/6554): Prevent Layout/RescueEnsureAlignment cop from breaking on block assignment when assignment is on a separate line. ([@timmcanty][])
 * [#6343](https://github.com/rubocop-hq/rubocop/pull/6343): Optimise `--auto-gen-config` when `Metrics/LineLength` cop is disabled. ([@tom-lord][])
 * [#6389](https://github.com/rubocop-hq/rubocop/pull/6389): Fix false negative for `Style/TrailingCommaInHashLitera`/`Style/TrailingCommaInArrayLiteral` when there is a comment in the last line. ([@bayandin][])
+* [#6566](https://github.com/rubocop-hq/rubocop/issues/6566): Fix false positive for `Layout/EmptyLinesAroundAccessModifier` when at the end of specifying a superclass is missing blank line. ([@koic][])
 
 ## 0.61.1 (2018-12-06)
 

lib/rubocop/cop/layout/empty_lines_around_access_modifier.rb

@@ -38,17 +38,24 @@ def initialize(config = nil, options = nil)
         def on_class(node)
           _name, superclass, _body = *node
 
-          @class_or_module_def = superclass || node.source_range
+          @class_or_module_def_first_line = if superclass
+                                              superclass.first_line
+                                            else
+                                              node.source_range.first_line
+                                            end
+          @class_or_module_def_last_line = node.source_range.last_line
         end
 
         def on_module(node)
-          @class_or_module_def = node.source_range
+          @class_or_module_def_first_line = node.source_range.first_line
+          @class_or_module_def_last_line = node.source_range.last_line
         end
 
         def on_sclass(node)
           self_node, _body = *node
 
-          @class_or_module_def = self_node.source_range
+          @class_or_module_def_first_line = self_node.source_range.first_line
+          @class_or_module_def_last_line = self_node.source_range.last_line
         end
 
         def on_block(node)
@@ -106,9 +113,9 @@ def empty_lines_around?(node)
         end
 
         def class_def?(line)
-          return false unless @class_or_module_def
+          return false unless @class_or_module_def_first_line
 
-          line == @class_or_module_def.first_line + 1
+          line == @class_or_module_def_first_line + 1
         end
 
         def block_start?(line)
@@ -118,9 +125,9 @@ def block_start?(line)
         end
 
         def body_end?(line)
-          return false unless @class_or_module_def
+          return false unless @class_or_module_def_last_line
 
-          line == @class_or_module_def.last_line - 1
+          line == @class_or_module_def_last_line - 1
         end
 
         def message(node)

spec/rubocop/cop/layout/empty_lines_around_access_modifier_spec.rb

@@ -286,6 +286,17 @@ def test; end
       RUBY
     end
 
+    it 'accepts missing blank line when at the end of specifying ' \
+       'a superclass' do
+      expect_no_offenses(<<-RUBY.strip_indent)
+        class Test < Base
+          def test; end
+
+          #{access_modifier}
+        end
+      RUBY
+    end
+
     it 'requires blank line when next line started with end' do
       inspect_source(<<-RUBY.strip_indent)
         class Test