Autofix for Style/StructInheritance

CHANGELOG.md

@@ -12,6 +12,7 @@
 * [#7786](https://github.com/rubocop-hq/rubocop/pull/7786): Support Ruby 2.7's pattern match for `Layout/ElseAlignment` cop. ([@koic][])
 * [#7784](https://github.com/rubocop-hq/rubocop/pull/7784): Support Ruby 2.7's numbered parameter for `Lint/SafeNavigationChain`. ([@koic][])
 * [#7331](https://github.com/rubocop-hq/rubocop/issues/7331): Add `forbidden` option to `Style/ModuleFunction` cop. ([@weh][])
+* [#7499](https://github.com/rubocop-hq/rubocop/pull/7499): Autocorrection for `Style/StructInheritance`. ([@bubaflub][])
 
 ### Bug fixes
 
@@ -4411,3 +4412,4 @@
 [@nikitasakov]: https://github.com/nikitasakov
 [@dmolesUC]: https://github.com/dmolesUC
 [@yuritomanek]: https://github.com/yuritomanek
+[@bubaflub]: https://github.com/bubaflub

config/default.yml

@@ -3758,7 +3758,9 @@ Style/StructInheritance:
   Description: 'Checks for inheritance from Struct.new.'
   StyleGuide: '#no-extend-struct-new'
   Enabled: true
+  SafeAutoCorrect: false
   VersionAdded: '0.29'
+  VersionChanged: '0.81'
 
 Style/SymbolArray:
   Description: 'Use %i or %I for arrays of symbols.'

lib/rubocop/ast/node/class_node.rb

@@ -6,9 +6,9 @@ module AST
     # node when the builder constructs the AST, making its methods available
     # to all `class` nodes within RuboCop.
     class ClassNode < Node
-      # The identifer for this `class` node.
+      # The identifier for this `class` node.
       #
-      # @return [Node] the identifer of the class
+      # @return [Node] the identifier of the class
       def identifier
         node_parts[0]
       end

lib/rubocop/cop/style/struct_inheritance.rb

@@ -20,6 +20,8 @@ module Style
       #     end
       #   end
       class StructInheritance < Cop
+        include RangeHelp
+
         MSG = "Don't extend an instance initialized by `Struct.new`. " \
               'Use a block to customize the struct.'
 
@@ -33,6 +35,48 @@ def on_class(node)
           {(send (const nil? :Struct) :new ...)
            (block (send (const nil? :Struct) :new ...) ...)}
         PATTERN
+
+        def autocorrect(class_node)
+          lambda do |corrector|
+            return nil if struct_definition_has_block?(class_node)
+
+            remove_class_keyword(class_node, corrector)
+
+            corrector.replace(class_node.loc.operator, '=')
+
+            transform_class_body(class_node, corrector)
+          end
+        end
+
+        private
+
+        def struct_definition_has_block?(class_node)
+          class_node.parent_class.is_a?(RuboCop::AST::BlockNode)
+        end
+
+        def remove_class_keyword(class_node, corrector)
+          corrector.remove(
+            range_with_surrounding_space(
+              range: class_node.loc.keyword,
+              side: :right
+            )
+          )
+        end
+
+        def transform_class_body(class_node, corrector)
+          body = class_node.body
+
+          if body
+            corrector.insert_after(class_node.parent_class.source_range, ' do')
+          else
+            corrector.remove(
+              range_with_surrounding_space(
+                range: class_node.loc.end,
+                side: :right
+              )
+            )
+          end
+        end
       end
     end
   end

manual/cops_style.md

@@ -6747,7 +6747,7 @@ This cop identifies places where `lstrip.rstrip` can be replaced by
 
 Enabled by default | Safe | Supports autocorrection | VersionAdded | VersionChanged
 --- | --- | --- | --- | ---
-Enabled | Yes | No | 0.29 | -
+Enabled | Yes | Yes (Unsafe) | 0.29 | 0.81
 
 This cop checks for inheritance from Struct.new.
 

spec/rubocop/cop/style/struct_inheritance_spec.rb

@@ -46,4 +46,66 @@ def age
       end
     RUBY
   end
+
+  it 'autocorrects simple inline class with no block' do
+    new_source = autocorrect_source(<<~RUBY)
+      class Person < Struct.new(:first_name, :last_name)
+      end
+    RUBY
+
+    expect(new_source).to eq(<<~RUBY)
+      Person = Struct.new(:first_name, :last_name)
+    RUBY
+  end
+
+  it 'autocorrects a class with a body' do
+    new_source = autocorrect_source(<<~RUBY)
+      class Person < Struct.new(:first_name, :last_name)
+        def age
+          42
+        end
+      end
+    RUBY
+
+    expect(new_source).to eq(<<~RUBY)
+      Person = Struct.new(:first_name, :last_name) do
+        def age
+          42
+        end
+      end
+    RUBY
+  end
+
+  it 'ignores a class with an empty block and empty body' do
+    original_source = <<~RUBY
+      class Person < Struct.new(:first_name, :last_name) do end
+      end
+    RUBY
+
+    expect(autocorrect_source(original_source)).to eq(original_source)
+  end
+
+  it 'ignores a class with a body and an empty block' do
+    original_source = <<~RUBY
+      class Person < Struct.new(:first_name, :last_name) do end
+        def age
+          42
+        end
+      end
+    RUBY
+
+    expect(autocorrect_source(original_source)).to eq(original_source)
+  end
+
+  it 'ignores a class with a body and a block' do
+    original_source = <<~RUBY
+      class Person < Struct.new(:first_name, :last_name) do def baz; end end
+        def age
+          42
+        end
+      end
+    RUBY
+
+    expect(autocorrect_source(original_source)).to eq(original_source)
+  end
 end