class_docstr: Abstract class for integration testing concrete Metadata implementations.
  
  Subclasses should override metadata() to return an instance of Metadata that
  has not been entered.
class_docstr_tok: ["Abstract","class","for","integration","testing","concrete","Metadata","implementations",".","Subclasses","should","override","metadata","(",")","to","return","an","instance","of","Metadata","that","has","not","been","entered","."]
code: def metadata(self):
      raise NotImplementedError("metadata() was not implemented")
  
imports: from typing import Mapping
  import tensorflow
  from tfx.orchestration import data_types
  from tfx.orchestration import metadata
  from tfx.types import artifact_utils
  from tfx.types import standard_artifacts
  from tfx.types.artifact import ArtifactState
  from ml_metadata.proto import metadata_store_pb2
label_desc: Use image node_id 4 for calling the MetadataTest obj's underlying member method code with example usage: obj.metadata() without return types