Harshavardhana <******@****.***> 1723857894 -0700

    assertThat(e.getMessage()).contains(ERROR_REUSE_EDGE);
  }

  @Test
  public void addEdge_parallelSelfLoopEdge_notAllowed() {
    assume().that(graphIsMutable()).isTrue();
    assume().that(network.allowsSelfLoops()).isTrue();
    assume().that(network.allowsParallelEdges()).isFalse();

    addEdge(N1, N1, E11);
    IllegalArgumentException e =
        assertThrows(

    assertThat(e.getMessage()).contains(ERROR_REUSE_EDGE);
  }

  @Test
  public void addEdge_parallelSelfLoopEdge_notAllowed() {
    assume().that(graphIsMutable()).isTrue();
    assume().that(network.allowsSelfLoops()).isTrue();
    assume().that(network.allowsParallelEdges()).isFalse();

    addEdge(N1, N1, E11);
    IllegalArgumentException e =
        assertThrows(

  public void putEdge_doesntAllowSelfLoops() {
    assume().that(graphIsMutable()).isTrue();
    assume().that(graph.allowsSelfLoops()).isFalse();

    IllegalArgumentException e =
        assertThrows(IllegalArgumentException.class, () -> putEdge(N1, N1));
    assertThat(e).hasMessageThat().contains(ERROR_SELF_LOOP);
  }

  @Test
  public void putEdge_allowsSelfLoops() {
    assume().that(graphIsMutable()).isTrue();

  public void putEdge_doesntAllowSelfLoops() {
    assume().that(graphIsMutable()).isTrue();
    assume().that(graph.allowsSelfLoops()).isFalse();

    IllegalArgumentException e =
        assertThrows(IllegalArgumentException.class, () -> putEdge(N1, N1));
    assertThat(e).hasMessageThat().contains(ERROR_SELF_LOOP);
  }

  @Test
  public void putEdge_allowsSelfLoops() {
    assume().that(graphIsMutable()).isTrue();

    assertThat(e).hasMessageThat().contains(ERROR_REUSE_EDGE);
  }

  @Test
  public void addEdge_parallelSelfLoopEdge_notAllowed() {
    assume().that(graphIsMutable()).isTrue();
    assume().that(network.allowsSelfLoops()).isTrue();
    assume().that(network.allowsParallelEdges()).isFalse();

    addEdge(N1, N1, E11);
    IllegalArgumentException e =
        assertThrows(

    assertThat(e).hasMessageThat().contains(ERROR_REUSE_EDGE);
  }

  @Test
  public void addEdge_parallelSelfLoopEdge_notAllowed() {
    assume().that(graphIsMutable()).isTrue();
    assume().that(network.allowsSelfLoops()).isTrue();
    assume().that(network.allowsParallelEdges()).isFalse();

    addEdge(N1, N1, E11);
    IllegalArgumentException e =
        assertThrows(

## Read the Tutorial first

You could still use most of the features in **FastAPI** with the knowledge from the main [Tutorial - User Guide](../tutorial/index.md){.internal-link target=_blank}.

And the next sections assume you already read it, and assume that you know those main ideas.

## External Courses

/// tip

The next sections are **not necessarily "advanced"**.

And it's possible that for your use case, the solution is in one of them.

///

## Read the Tutorial first

The next sections assume you already read the main [Tutorial - User Guide: Security](../../tutorial/security/index.md){.internal-link target=_blank}.

  /*
   * TODO: consider adding MultisetFeatures.SUPPORTS_SET_COUNT. Currently we
   * assume that using setCount() to increase the count is permitted iff add()
   * is permitted and similarly for decrease/remove(). We assume that a
   * setCount() no-op is permitted if either add() or remove() is permitted,
   * though we also allow it to "succeed" if neither is permitted.
   */