code: def test_list_runs(self):
      # We can't control the timestamps of events written to disk (without
      # manually reading the tfrecords, modifying the data, and writing
      # them back out), so we provide a fake multiplexer instead.
      start_times = {
          "second_2": 2.0,
          "first": 1.5,
          "no_time": None,
          "second_1": 2.0,
      }
  
      class FakeMultiplexer:
          def Runs(multiplexer):
              result = ["second_2", "first", "no_time", "second_1"]
              self.assertCountEqual(result, start_times)
              return result
  
          def FirstEventTimestamp(multiplexer, run):
              self.assertIn(run, start_times)
              result = start_times[run]
              if result is None:
                  raise ValueError("No event timestep could be found")
              else:
                  return result
  
      multiplexer = FakeMultiplexer()
      provider = data_provider.MultiplexerDataProvider(
          multiplexer, "fake_logdir"
      )
      result = provider.list_runs(self.ctx, experiment_id="unused")
      self.assertCountEqual(
          result,
          [
              base_provider.Run(
                  run_id=run, run_name=run, start_time=start_time
              )
              for (run, start_time) in start_times.items()
          ],
      )
  
imports: import os
  import numpy
  from tensorboard import context
  from tensorboard.backend.event_processing import data_provider
  from tensorboard.backend.event_processing import plugin_event_multiplexer
  from tensorboard.compat.proto import summary_pb2
  from tensorboard.data import provider
  from tensorboard.plugins.graph import metadata
  from tensorboard.plugins.histogram import metadata
  from tensorboard.plugins.histogram import summary_v2
  from tensorboard.plugins.scalar import metadata
  from tensorboard.plugins.scalar import summary_v2
  from tensorboard.plugins.image import metadata
  from tensorboard.plugins.image import summary_v2
  from tensorboard.util import tensor_util
  import tensorflow.compat.v1
  import tensorflow.compat.v2
label_desc: Use image node_id 7 for calling the MultiplexerDataProviderTest obj's underlying member method code with example usage: obj.test_list_runs() and returns: result, result