code: def test_get_current_revision_error_if_starting_rev_given_online(
      self,
  ):
      context = self.make_one(
          connection=self.connection, opts={"starting_rev": "boo"}
      )
      assert_raises(CommandError, context.get_current_revision)
  
imports: from sqlalchemy import Column
  from sqlalchemy import inspect
  from sqlalchemy import MetaData
  from sqlalchemy import String
  from sqlalchemy import Table
  from alembic import migration
  from alembic.testing import assert_raises
  from alembic.testing import assert_raises_message
  from alembic.testing import config
  from alembic.testing import eq_
  from alembic.testing import mock
  from alembic.testing.fixtures import TestBase
  from alembic.util import CommandError
label_desc: Use image node_id 13 for calling the TestMigrationContext obj's underlying member method code with example usage: obj.test_get_current_revision_error_if_starting_rev_given_online() without return types