prevent abstract class tables to leak columns to other tables

lib/mini_record/auto_schema.rb

@@ -11,7 +11,7 @@ def schema_tables
       end
 
       def table_definition
-        return superclass.table_definition unless superclass == ActiveRecord::Base
+        return superclass.table_definition unless (superclass == ActiveRecord::Base) || (superclass.respond_to?(:abstract_class?) && superclass.abstract_class?)
 
         @_table_definition ||= begin
                                  tb = ActiveRecord::ConnectionAdapters::TableDefinition.new(connection)
@@ -21,7 +21,7 @@ def table_definition
       end
 
       def indexes
-        return superclass.indexes unless superclass == ActiveRecord::Base
+        return superclass.indexes unless (superclass == ActiveRecord::Base) || (superclass.respond_to?(:abstract_class?) && superclass.abstract_class?)
 
         @_indexes ||= {}
       end

test/test_mini_record.rb

@@ -596,4 +596,26 @@ class Bar < Foo
     refute_includes tables, ''
     assert_includes tables, 'bars'
   end
+
+  it 'should prevent abstract table class to leak columns to other tables' do
+
+    class Base < ActiveRecord::Base
+      self.abstract_class = true
+    end
+
+    class User < Base
+      col :name
+    end
+
+    class Book < Base
+      col :title
+      col :author
+    end
+
+    User.auto_upgrade!
+    Book.auto_upgrade!
+
+    assert_equal ['id', 'name'], User.db_columns.sort
+    assert_equal ['author', 'id', 'title'], Book.db_columns.sort
+  end
 end