Merge pull request #49911 from a5-stable/active_record_base_table_name

return nil for `ActiveRecord::Base.table_name`

(cherry picked from commit 404ce7e)

activerecord/CHANGELOG.md

@@ -1,3 +1,8 @@
+*   `ActiveRecord::Base.table_name` now returns `nil` instead of raising
+    "undefined method `abstract_class?` for Object:Class".
+
+    *a5-stable*
+
 *   Fix upserting for custom `:on_duplicate` and `:unique_by` consisting of all
     inserts keys.
 

activerecord/lib/active_record/model_schema.rb

@@ -284,8 +284,10 @@ def quoted_table_name
 
       # Computes the table name, (re)sets it internally, and returns it.
       def reset_table_name # :nodoc:
-        self.table_name = if abstract_class?
-          superclass == Base ? nil : superclass.table_name
+        self.table_name = if self == Base
+          nil
+        elsif abstract_class?
+          superclass.table_name
         elsif superclass.abstract_class?
           superclass.table_name || compute_table_name
         else

activerecord/test/cases/base_test.rb

@@ -524,6 +524,10 @@ def test_table_name_based_on_model_name
     assert_equal "posts", PostRecord.table_name
   end
 
+  def test_table_name_for_base_class
+    assert_nil ActiveRecord::Base.table_name
+  end
+
   def test_null_fields
     assert_nil Topic.find(1).parent_id
     assert_nil Topic.create("title" => "Hey you").parent_id