code: def test_dummy_metric():
      class DummyMetric(AbstractMetric):
          pass
  
      DummyMetric.__abstractmethods__ = set()
      m = DummyMetric(
          "dummy_metric", "A test metric", ("service", "tenant")
      )
      assert isinstance(m, AbstractMetric)
      assert m.name == "dummy_metric"
      assert m.description == "A test metric"
      assert m.tag_keys == ("service", "tenant")
      assert m.type is None
      assert m._init() is None
      assert m.record() is None
      assert m._record() is None
  
file_path: mars/mars/metrics/backends/tests/test_metric.py
imports: import pytest
  from ..metric import AbstractMetric, AbstractCounter, AbstractGauge, AbstractMeter, AbstractHistogram
label_desc: Use image node_id 2 for calling a global function with example usage: test_dummy_metric() without return types