"Expiration": "2019-02-20T19:56:59-08:00",
        "AccessKeyId": "K9DTIMUVZXEXJL3ATUOY"
    }
}
```

### Testing an example with `assume-role.go`

The included program in this directory can also be used for testing:

``` shell
$ go run assume-role.go -u foobar -p foo12345 -d
Only displaying credentials:
AccessKeyID: 27YDRYEM0S9B44AJJX9X
SecretAccessKey: LHPdHeaLiYk+pDZ3hgN3sdwXpJC2qbhBfZ8ii9Z3

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

    assume().that(graphIsMutable()).isTrue();
    assume().that(graph.allowsSelfLoops()).isTrue();

    graphAsMutableGraph.putEdge(N1, N1);
    assertThat(graphAsMutableGraph.putEdge(N1, N1)).isFalse();
  }

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

    putEdge(N1, N2);
    putEdge(N2, N1);

    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(

  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(

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}.

    assume().that(graphIsMutable()).isTrue();
    assume().that(network.allowsParallelEdges()).isTrue();
    assume().that(network.allowsSelfLoops()).isTrue();

    addEdge(N1, N1, E11);
    addEdge(N1, N1, E11_A);
    addEdge(N1, N2, E12);
    assertTrue(networkAsMutableNetwork.removeEdge(E11_A));
    assertThat(network.edgesConnecting(N1, N1)).containsExactly(E11);