Merge pull request #1175 from koic/fix_an_error_for_rails_unknown_env

[Fix #1172] Fix an error for `Rails/UnknownEnv`

changelog/fix_an_error_for_rails_unknown_env.md

@@ -0,0 +1 @@
+* [#1172](https://github.com/rubocop/rubocop-rails/issues/1172): Fix an error for `Rails/UnknownEnv` when using Rails 7.1. ([@koic][])

lib/rubocop/cop/rails/unknown_env.rb

@@ -87,9 +87,9 @@ def unknown_env_name?(name)
 
         def environments
           @environments ||= begin
-            e = cop_config['Environments']
-            e += ['local'] if target_rails_version >= 7.1
-            e
+            environments = cop_config['Environments'] || []
+            environments << 'local' if target_rails_version >= 7.1
+            environments
           end
         end
       end

spec/rubocop/cop/rails/unknown_env_spec.rb

@@ -91,5 +91,20 @@
         Rails.env == 'local'
       RUBY
     end
+
+    context 'when `Environments` is nil' do
+      let(:cop_config) do
+        {
+          'Environments' => nil
+        }
+      end
+
+      it 'accepts local as an environment name' do
+        expect_no_offenses(<<~RUBY)
+          Rails.env.local?
+          Rails.env == 'local'
+        RUBY
+      end
+    end
   end
 end