Update test/config_test.rb

Co-authored-by: Sam Bostock <sambostock@users.noreply.github.com>

test/config_test.rb

@@ -34,25 +34,26 @@ def test_config_is_unchanged
   def test_config_has_no_redundant_entries
     config = RuboCop::ConfigLoader.load_file("rubocop.yml")
     default_config = RuboCop::ConfigLoader.default_configuration
+    redundant_config = Hash.new { |hash, key| hash[key] = {} }
 
     # This entry is not a cop.
     config.delete("inherit_mode")
 
     config.each do |cop_name, cop_config|
       default_cop_config = default_config.fetch(cop_name)
       cop_config.each do |key, value|
-        error_message = <<~ERROR
-          Error: #{cop_name} was configured with the same value as the default
-          RuboCop configuration.
+        default_value = default_cop_config[key]
+        redundant_config[cop_name][key] = value if value == default_value
+      end
+    end
 
-          #{cop_name}:
-            #{key}: #{value}
+    flunk(<<~ERROR.chomp) unless redundant_config.empty?
+      Error: The following config values are the same as the default Rubocop configuration:
 
-          Please remove the configuration as it is unnecessary.
-        ERROR
+      #{redundant_config.to_yaml.sub(/\A---\n/, "").chomp}
 
-        refute_equal(default_cop_config[key], value, error_message)
-      end
-    end
+      Please remove these entries from the configuration, as they are unnecessary.
+    ERROR
+  end
   end
 end