[Fix #1173] Fix an error for Rails/RedundantActiveRecordAllMethod cop

Fixes #1173.

This PR fixes an error for `Rails/RedundantActiveRecordAllMethod` cop
when used with RuboCop 1.51 or lower.
Additionally, it introduces a CI matrix for regression testing with
the oldest supported RuboCop version.

.github/workflows/test.yml

@@ -0,0 +1,34 @@
+name: CI
+
+on:
+  push:
+    branches:
+      - master
+  pull_request:
+  workflow_dispatch:
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.head_ref || github.run_id }}
+  cancel-in-progress: true
+
+jobs:
+  oldest_supported_rubocop:
+    runs-on: ubuntu-latest
+    name: The oldest supported RuboCop version
+    steps:
+      - uses: actions/checkout@v4
+      - name: Use the oldest supported RuboCop
+        run: |
+          sed -e "/gem 'rubocop', github: 'rubocop\/rubocop'/d" \
+              -e "/gem 'rubocop-performance',/d" \
+              -e "/gem 'rubocop-rspec',/d" -i Gemfile
+          cat << EOF > Gemfile.local
+            gem 'rubocop', '1.33.0' # Specify the oldest supported RuboCop version
+          EOF
+      - name: set up Ruby
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: 2.7
+          bundler-cache: true
+      - name: spec
+        run: bundle exec rake spec

changelog/fix_error_for_rails_redundant_active_record_all_method.md

@@ -0,0 +1 @@
+* [#1173](https://github.com/rubocop/rubocop-rails/issues/1173): Fix an error for `Rails/RedundantActiveRecordAllMethod` cop when used with RuboCop 1.51 or lower. ([@koic][])

lib/rubocop/cop/rails/redundant_active_record_all_method.rb

@@ -3,6 +3,35 @@
 module RuboCop
   module Cop
     module Rails
+      # TODO: In the future, please support only RuboCop 1.52+ and use `RuboCop::Cop::AllowedReceivers`:
+      #       https://github.com/rubocop/rubocop/blob/v1.52.0/lib/rubocop/cop/mixin/allowed_receivers.rb
+      #       At that time, this duplicated module implementation can be removed.
+      module AllowedReceivers
+        def allowed_receiver?(receiver)
+          receiver_name = receiver_name(receiver)
+
+          allowed_receivers.include?(receiver_name)
+        end
+
+        def receiver_name(receiver)
+          return receiver_name(receiver.receiver) if receiver.receiver && !receiver.receiver.const_type?
+
+          if receiver.send_type?
+            if receiver.receiver
+              "#{receiver_name(receiver.receiver)}.#{receiver.method_name}"
+            else
+              receiver.method_name.to_s
+            end
+          else
+            receiver.source
+          end
+        end
+
+        def allowed_receivers
+          cop_config.fetch('AllowedReceivers', [])
+        end
+      end
+
       # Detect redundant `all` used as a receiver for Active Record query methods.
       #
       # @safety
@@ -172,35 +201,6 @@ def possible_enumerable_block_method?(node)
         def offense_range(node)
           range_between(node.loc.selector.begin_pos, node.source_range.end_pos)
         end
-
-        # TODO: In the future, please support only RuboCop 1.52+ and use `RuboCop::Cop::AllowedReceivers`:
-        #       https://github.com/rubocop/rubocop/blob/v1.52.0/lib/rubocop/cop/mixin/allowed_receivers.rb
-        #       At that time, this duplicated module implementation can be removed.
-        module AllowedReceivers
-          def allowed_receiver?(receiver)
-            receiver_name = receiver_name(receiver)
-
-            allowed_receivers.include?(receiver_name)
-          end
-
-          def receiver_name(receiver)
-            return receiver_name(receiver.receiver) if receiver.receiver && !receiver.receiver.const_type?
-
-            if receiver.send_type?
-              if receiver.receiver
-                "#{receiver_name(receiver.receiver)}.#{receiver.method_name}"
-              else
-                receiver.method_name.to_s
-              end
-            else
-              receiver.source
-            end
-          end
-
-          def allowed_receivers
-            cop_config.fetch('AllowedReceivers', [])
-          end
-        end
       end
     end
   end