No correction for errors.details[:n] << v

Fixes for Rails/DeprecatedActiveModelErrorsMethods:
- Fixed a bad autocorrection of `errors.details[:name] << value`.
  There isn't really a correct replacement for this one.
- Did some refactors prompted by rubocop complaints.
- Fixed a misspelling of autocorrectable.
- Added missing correction assertions to test cases.

changelog/fix_deprecated_errors_bad_details_autocorrection.md

@@ -0,0 +1 @@
+* [#741](https://github.com/rubocop/rubocop-rails/pull/741): Fix a bad autocorrection for `errors.details[:name] << value` in Rails/DeprecatedActiveModelErrorsMethods. ([@BrianHawley][])

lib/rubocop/cop/rails/deprecated_active_model_errors_methods.rb

@@ -37,7 +37,7 @@ class DeprecatedActiveModelErrorsMethods < Base
         extend AutoCorrector
 
         MSG = 'Avoid manipulating ActiveModel errors as hash directly.'
-        AUTOCORECTABLE_METHODS = %i[<< clear keys].freeze
+        AUTOCORRECTABLE_METHODS = %i[<< clear keys].freeze
 
         MANIPULATIVE_METHODS = Set[
           *%i[
@@ -109,7 +109,7 @@ def on_send(node)
             next if node.method?(:keys) && target_rails_version <= 6.0
 
             add_offense(node) do |corrector|
-              next unless AUTOCORECTABLE_METHODS.include?(node.method_name)
+              next if skip_autocorrect?(node)
 
               autocorrect(corrector, node)
             end
@@ -118,6 +118,13 @@ def on_send(node)
 
         private
 
+        def skip_autocorrect?(node)
+          receiver = node.receiver.receiver
+          !AUTOCORRECTABLE_METHODS.include?(node.method_name) || (
+            receiver&.send_type? && receiver&.method?(:details) && node.method?(:<<)
+          )
+        end
+
         def autocorrect(corrector, node)
           receiver = node.receiver
 

spec/rubocop/cop/rails/deprecated_active_model_errors_methods_spec.rb

@@ -135,6 +135,8 @@
           user.errors.details[:name] << {}
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Avoid manipulating ActiveModel errors as hash directly.
         RUBY
+
+        expect_no_corrections
       end
 
       context 'when assigning' do
@@ -318,6 +320,8 @@ def expect_no_corrections_if_model_file(file_path)
           errors.details[:name] << {}
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^ Avoid manipulating ActiveModel errors as hash directly.
         RUBY
+
+        expect_no_corrections_if_model_file(file_path)
       end
 
       context 'when assigning' do