Merge pull request rubocop#688 from koic/support_autocorrect_for_rail…

…s_deprecated_active_model_errors_methods

Support auto-correction for `Rails/DeprecatedActiveModelErrorsMethods`

changelog/new_support_autocorrect_for_rails_deprecated_active_model_errors_methods.md

@@ -0,0 +1 @@
+* [#688](https://github.com/rubocop/rubocop-rails/pull/688): Support auto-correction for `Rails/DeprecatedActiveModelErrorsMethods`. ([@koic][])

config/default.yml

@@ -271,6 +271,7 @@ Rails/DeprecatedActiveModelErrorsMethods:
   Enabled: pending
   Safe: false
   VersionAdded: '2.14'
+  VersionChanged: '<<next>>'
 
 Rails/DuplicateAssociation:
   Description: "Don't repeat associations in a model."

lib/rubocop/cop/rails/deprecated_active_model_errors_methods.rb

@@ -27,7 +27,11 @@ module Rails
       #   user.errors.delete(:name)
       #
       class DeprecatedActiveModelErrorsMethods < Base
+        include RangeHelp
+        extend AutoCorrector
+
         MSG = 'Avoid manipulating ActiveModel errors as hash directly.'
+        AUTOCORECTABLE_METHODS = %i[<< clear].freeze
 
         MANIPULATIVE_METHODS = Set[
           *%i[
@@ -89,12 +93,47 @@ class DeprecatedActiveModelErrorsMethods < Base
 
         def on_send(node)
           any_manipulation?(node) do
-            add_offense(node)
+            add_offense(node) do |corrector|
+              next unless AUTOCORECTABLE_METHODS.include?(node.method_name)
+
+              autocorrect(corrector, node)
+            end
           end
         end
 
         private
 
+        def autocorrect(corrector, node)
+          receiver = node.receiver
+
+          if receiver.receiver.method?(:messages)
+            corrector.remove(receiver.receiver.loc.dot)
+            corrector.remove(receiver.receiver.loc.selector)
+          end
+
+          range = offense_range(node, receiver)
+          replacement = replacement(node, receiver)
+
+          corrector.replace(range, replacement)
+        end
+
+        def offense_range(node, receiver)
+          range_between(receiver.receiver.source_range.end_pos, node.source_range.end_pos)
+        end
+
+        def replacement(node, receiver)
+          key = receiver.first_argument.source
+
+          case node.method_name
+          when :<<
+            value = node.first_argument.source
+
+            ".add(#{key}, #{value})"
+          when :clear
+            ".delete(#{key})"
+          end
+        end
+
         def receiver_matcher(node)
           model_file? ? receiver_matcher_inside_model(node) : receiver_matcher_outside_model(node)
         end

spec/rubocop/cop/rails/deprecated_active_model_errors_methods_spec.rb

@@ -3,11 +3,15 @@
 RSpec.describe RuboCop::Cop::Rails::DeprecatedActiveModelErrorsMethods, :config do
   shared_examples 'errors call with explicit receiver' do
     context 'when modifying errors' do
-      it 'registers an offense' do
+      it 'registers and corrects an offense' do
         expect_offense(<<~RUBY, file_path)
           user.errors[:name] << 'msg'
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^ Avoid manipulating ActiveModel errors as hash directly.
         RUBY
+
+        expect_correction(<<~RUBY)
+          user.errors.add(:name, 'msg')
+        RUBY
       end
 
       context 'when assigning' do
@@ -18,14 +22,31 @@
           RUBY
         end
       end
+
+      context 'when using `clear` method' do
+        it 'registers and corrects an offense' do
+          expect_offense(<<~RUBY, file_path)
+            user.errors[:name].clear
+            ^^^^^^^^^^^^^^^^^^^^^^^^ Avoid manipulating ActiveModel errors as hash directly.
+          RUBY
+
+          expect_correction(<<~RUBY)
+            user.errors.delete(:name)
+          RUBY
+        end
+      end
     end
 
     context 'when modifying errors.messages' do
-      it 'registers an offense' do
+      it 'registers and corrects an offense' do
         expect_offense(<<~RUBY, file_path)
           user.errors.messages[:name] << 'msg'
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Avoid manipulating ActiveModel errors as hash directly.
         RUBY
+
+        expect_correction(<<~RUBY)
+          user.errors.add(:name, 'msg')
+        RUBY
       end
 
       context 'when assigning' do