Fix enum conflict message grammar.

Format the error message so that the correct article is used according
to the method type (e.g. "an instance method", "a class method").

Fallback to omitting the method type altogether if unknown, producing
the generic wording "a method".

Fixes rails#55364

Co-Authored-By: Jean Boussier <[email protected]>

Author: callmesangio

activerecord/lib/active_record/enum.rb

@@ -383,25 +383,25 @@ def assert_valid_enum_options(options)
 
       ENUM_CONFLICT_MESSAGE = \
         "You tried to define an enum named \"%{enum}\" on the model \"%{klass}\", but " \
-        "this will generate a %{type} method \"%{method}\", which is already defined " \
+        "this will generate %{type} method \"%{method}\", which is already defined " \
         "by %{source}."
       private_constant :ENUM_CONFLICT_MESSAGE
 
       def detect_enum_conflict!(enum_name, method_name, klass_method = false)
         if klass_method && dangerous_class_method?(method_name)
-          raise_conflict_error(enum_name, method_name, type: "class")
+          raise_conflict_error(enum_name, method_name, "a class")
         elsif klass_method && method_defined_within?(method_name, Relation)
-          raise_conflict_error(enum_name, method_name, type: "class", source: Relation.name)
+          raise_conflict_error(enum_name, method_name, "a class", source: Relation.name)
         elsif klass_method && method_name.to_sym == :id
-          raise_conflict_error(enum_name, method_name)
+          raise_conflict_error(enum_name, method_name, "an instance")
         elsif !klass_method && dangerous_attribute_method?(method_name)
-          raise_conflict_error(enum_name, method_name)
+          raise_conflict_error(enum_name, method_name, "an instance")
         elsif !klass_method && method_defined_within?(method_name, _enum_methods_module, Module)
-          raise_conflict_error(enum_name, method_name, source: "another enum")
+          raise_conflict_error(enum_name, method_name, "an instance", source: "another enum")
         end
       end
 
-      def raise_conflict_error(enum_name, method_name, type: "instance", source: "Active Record")
+      def raise_conflict_error(enum_name, method_name, type, source: "Active Record")
         raise ArgumentError, ENUM_CONFLICT_MESSAGE % {
           enum: enum_name,
           klass: name,

activerecord/test/cases/enum_test.rb

@@ -584,6 +584,22 @@ def self.name; "Book"; end
     end
   end
 
+  test "conflict message grammar" do
+    conflicts = {
+      column: /will generate a class method/,
+      logger: /will generate an instance method/,
+    }
+
+    conflicts.each do |name, pattern|
+      assert_raises(ArgumentError, match: pattern) do
+        Class.new(ActiveRecord::Base) do
+          self.table_name = "books"
+          enum name, [:value]
+        end
+      end
+    end
+  end
+
   test "overriding enum method should not raise" do
     assert_nothing_raised do
       Class.new(ActiveRecord::Base) do