code: def test_starting_rev_pre_context_cmd_w_no_startrev(self):
      env_file_fixture(
          """
  assert context.get_starting_revision_argument() == 'x'
  """
      )
      assert_raises_message(
          util.CommandError,
          "No starting revision argument is available.",
          command.current,
          self.cfg,
      )
  
imports: import re
  from alembic import command
  from alembic import util
  from alembic.testing import assert_raises_message
  from alembic.testing.env import _no_sql_testing_config
  from alembic.testing.env import clear_staging_env
  from alembic.testing.env import env_file_fixture
  from alembic.testing.env import multi_heads_fixture
  from alembic.testing.env import staging_env
  from alembic.testing.env import three_rev_fixture
  from alembic.testing.fixtures import capture_context_buffer
  from alembic.testing.fixtures import TestBase
label_desc: Use image node_id 7 for calling the OfflineEnvironmentTest obj's underlying member method code with example usage: obj.test_starting_rev_pre_context_cmd_w_no_startrev() without return types