abstract_base.rb

# DON'T call this _test.rb as you don't want it to run
module AbstractTest
  def test_the_abstract_thing
    klass.do_something
    assert something, klass.something
  end
end

user_document_test.rb

# This is a test and inherits the others tests.
class UserDocumentTest < Minitest::Test
  include AbstractTest
  
  protected
  def klass
    UserDocument
  end
end