addEdge(N1, N1, E11);
    addEdge(N1, N2, E12);
    assertThat(network.adjacentEdges(E11)).containsExactly(E12);
  }

  @Test
  public void edgesConnecting_selfLoop() {
    assume().that(network.allowsSelfLoops()).isTrue();

    addEdge(N1, N1, E11);
    assertThat(network.edgesConnecting(N1, N1)).containsExactly(E11);
    addEdge(N1, N2, E12);

        Graph graph3 = new Graph();
        addEdge(graph3, "a", "b");
        addEdge(graph3, "b", "c");
        addEdge(graph3, "b", "d");
        addEdge(graph3, "a", "d");

        Graph graph4 = new Graph();
        addEdge(graph4, "a", "b");
        addEdge(graph4, "b", "c");
        addEdge(graph4, "b", "d");
        addEdge(graph4, "a", "d");

        // v1-->v2
        graph.addEdge(v1, v2, new MetadataGraphEdge("1.1", true, null, null, 2, 1));
        graph.addEdge(v1, v2, new MetadataGraphEdge("1.2", true, null, null, 2, 2));

        // v1-->v3
        graph.addEdge(v1, v3, new MetadataGraphEdge("1.1", true, null, null, 2, 1));
        graph.addEdge(v1, v3, new MetadataGraphEdge("1.2", true, null, null, 4, 2));

        // v3-->v4

                if (vertex != null) {
                    addEdge(projectVertex, vertex, project, projectMap, force, safe);
                }
            } else {
                for (Vertex vertex : vertices.values()) {
                    addEdge(projectVertex, vertex, project, projectMap, force, safe);
                }
            }
        }
    }

    private void addEdge(
            Vertex fromVertex,

public class GraphTest {

    @Test
    void testCycle() throws Graph.CycleDetectedException {
        Graph graph = new Graph();
        graph.addEdge("a1", "a2");
        assertThrows(Graph.CycleDetectedException.class, () -> graph.addEdge("a2", "a1"));
    }

    @Test
    public void testPerf() throws IOException {
        List<String[]> data = new ArrayList<>();
        String k = null;

        // v1-->v2
        graph.addEdge(v1, v2, new MetadataGraphEdge("1.1", true, null, null, 2, 1));
        graph.addEdge(v1, v2, new MetadataGraphEdge("1.2", true, null, null, 2, 2));

        // v1-->v3
        graph.addEdge(v1, v3, new MetadataGraphEdge("1.1", true, null, null, 2, 1));
        graph.addEdge(v1, v3, new MetadataGraphEdge("1.2", true, null, null, 4, 2));

        // v3-->v4

                    // gathered with problem collector
                }
                return null;
            }
        };
    }

    private boolean addEdge(Path from, Path p, DefaultModelProblemCollector problems) {
        try {
            dag.addEdge(from.toString(), p.toString());
            return true;
        } catch (Graph.CycleDetectedException e) {
            problems.add(new DefaultModelProblem(

                    // gathered with problem collector
                }
                return null;
            }
        };
    }

    private boolean addEdge(Path from, Path p, DefaultModelProblemCollector problems) {
        try {
            dag.addEdge(from.toString(), p.toString());
            return true;
        } catch (Graph.CycleDetectedException e) {
            problems.add(new DefaultModelProblem(

  TF_CHECK_OK(scope.DoShapeInference(launch));
  scope.graph()->AddEdge(a.node(), 0, launch, 0);
  scope.graph()->AddEdge(b.node(), 0, launch, 1);
  scope.graph()->AddEdge(c.node(), 0, launch, 2);
  scope.graph()->AddEdge(d.node(), 0, launch, 3);
  scope.graph()->AddEdge(u.node(), 0, launch, 4);
  scope.graph()->AddEdge(v.node(), 0, launch, 5);
  scope.graph()->AddEdge(w.node(), 0, launch, 6);

  auto out0 =

	// recording the graph, its out-edges.
	var edges []stackCheckEdge
	maxHeight := 0
	ctxt := sc.ctxt
	// addEdge adds a stack growth out of this function to
	// function "target" or, if target == 0, a local stack growth
	// within the function.
	addEdge := func(growth int, target loader.Sym) {
		if graph {
			edges = append(edges, stackCheckEdge{growth, target})
		}
		height := growth