Fix support for namespaced fixtures with Rails 7.1

Author: benedikt

features/model_specs/transactional_examples.feature

@@ -104,3 +104,23 @@ Feature: Transactional examples
       """
     When I run `rspec spec/models/thing_spec.rb`
     Then the examples should all pass
+
+  Scenario: Run in transactions with namespaced fixture
+    Given a file named "spec/models/thing_spec.rb" with:
+      """ruby
+      require "rails_helper"
+
+      RSpec.describe Thing, type: :model do
+        fixtures 'namespaced/things'
+        it "fixture method defined" do
+          namespaced_things(:one)
+        end
+      end
+      """
+    Given a file named "spec/fixtures/namespaced/things.yml" with:
+      """
+      one:
+        name: MyString
+      """
+    When I run `rspec spec/models/thing_spec.rb`
+    Then the examples should all pass

lib/rspec/rails/fixture_support.rb

@@ -43,14 +43,14 @@ module Fixtures
             if ::Rails.version.to_f >= 7.1
               def fixtures(*args)
                 super.tap do
-                  fixture_sets.each_key do |fixture_name|
-                    proxy_method_warning_if_called_in_before_context_scope(fixture_name)
+                  fixture_sets.each_pair do |method_name, fixture_name|
+                    proxy_method_warning_if_called_in_before_context_scope(method_name, fixture_name)
                   end
                 end
               end
 
-              def proxy_method_warning_if_called_in_before_context_scope(fixture_name)
-                define_method(fixture_name) do |*args, **kwargs, &blk|
+              def proxy_method_warning_if_called_in_before_context_scope(method_name, fixture_name)
+                define_method(method_name) do |*args, **kwargs, &blk|
                   if RSpec.current_scope == :before_context_hook
                     RSpec.warn_with("Calling fixture method in before :context ")
                   else