class_docstr: Tests for shared/alert_table.py
docstr: Alert Table - Add Alerts
docstr_tok: ["Alert","Table","-","Add","Alerts"]
code: def test_add_alerts(self):
      """Alert Table - Add Alerts"""
      items = self.alert_table._table.scan()["Items"]
      assert_equal(3, len(items))
  
imports: from datetime import datetime
  import os
  from botocore.exceptions import ClientError
  from mock import ANY, MagicMock, patch
  from moto import mock_dynamodb2
  from nose.tools import assert_equal, assert_raises
  from streamalert.shared import alert, alert_table
  from tests.unit.helpers.aws_mocks import setup_mock_alerts_table
label_desc: Use image node_id 8 for calling the TestAlertTable obj's underlying member method code with example usage: obj.test_add_alerts() without return types