docstr: AlertPublisherRepository - is_valid_publisher() - Class
docstr_tok: ["AlertPublisherRepository","-","is_valid_publisher","(",")","-","Class"]
code: def test_is_valid_publisher_class():
      """AlertPublisherRepository - is_valid_publisher() - Class"""
      assert_true(
          AlertPublisherRepository.is_valid_publisher(SamplePublisher1)
      )
  
imports: from mock import patch
  from nose.tools import assert_true, assert_equal, assert_false
  from streamalert.alert_processor.helpers import _assemble_alert_publisher_for_output
  from streamalert.shared.publisher import AlertPublisherRepository, AlertPublisher, CompositePublisher, DefaultPublisher, Register, WrappedFunctionPublisher
  from tests.unit.streamalert.alert_processor.helpers import get_alert
label_desc: Use image node_id 1 for calling the TestAlertPublisherRepository obj's underlying member method code with example usage: obj.test_is_valid_publisher_class() without return types