docstr: Should raise an error if the target_node is not found in the graph
docstr_tok: ["Should","raise","an","error","if","the","target_node","is","not","found","in","the","graph"]
code: def test_node_not_in_graph(self, target_node, test_input):
      """Should raise an error if the target_node is not found in the graph"""
  
      sm = StructureModel()
      sm.add_edges_from(test_input)
  
      with pytest.raises(
          NodeNotFound,
          match=f"Node {target_node} not found in the graph",
      ):
          sm.get_target_subgraph(target_node)
  
imports: import pytest
  from networkx.exception import NodeNotFound
  from causalnex.structure import StructureModel
label_desc: Use image node_id 3 for calling the TestStructureModelGetTargetSubgraph obj's underlying member method code with example usage: obj.test_node_not_in_graph(target_node, test_input) without return types