code: def test_build_target(repo):
      graph = _build(repo, target="3")
      assert set(graph.nodes()) == {"3", "b.dvc", "a.dvc"}
      assert set(graph.edges()) == {("3", "a.dvc"), ("3", "b.dvc")}
  
file_path: dvc/tests/unit/command/test_dag.py
imports: import networkx
  import pytest
  from dvc.cli import main, parse_args
  from dvc.commands.dag import CmdDAG, _build, _show_ascii, _show_dot, _show_mermaid
label_desc: Use image node_id 4 for calling a global function with example usage: test_build_target(repo) without return types