* exception goes to the uncaught exception handler.
   */
  private fun interceptorThrowsRuntimeExceptionAsynchronous(network: Boolean) {
    val boom = RuntimeException("boom!")
    addInterceptor(network) { chain: Interceptor.Chain? -> throw boom }
    val executor = ExceptionCatchingExecutor()
    client =
      client.newBuilder()
        .dispatcher(Dispatcher(executor))
        .build()
    val request =

        override fun run() {
          throw RuntimeException("boom!")
        }
      }
    thread.start()
    thread.join()

    assertFailsWith<AssertionError> {
      testRule.afterEach(extensionContext)
    }.also { expected ->
      assertThat(expected).hasMessage("uncaught exception thrown during test")
      assertThat(expected.cause!!).hasMessage("boom!")
    }
  }

!!! tip "Tipp"

  private static final String ERROR_ADDED_PARALLEL_EDGE =
      "Should not be allowed to add a parallel edge.";
  private static final String ERROR_ADDED_SELF_LOOP =
      "Should not be allowed to add a self-loop edge.";
  static final String ERROR_SELF_LOOP = "self-loops are not allowed";

  @Test
  public void transitiveClosure_directedGraph() {

* Select "Python"
* Run the debugger with the option "`Python: Current File (Integrated Terminal)`".

It will then start the server with your **FastAPI** code, stop at your breakpoints, etc.

Here's how it might look:

<img src="/img/tutorial/debugging/image01.png">

---

If you use Pycharm, you can:

* Open the "Run" menu.
* Select the option "Debug...".
* Then a context menu shows up.

// initDataScanner will start the scanner in the background.
func initDataScanner(ctx context.Context, objAPI ObjectLayer) {
	go func() {
		r := rand.New(rand.NewSource(time.Now().UnixNano()))
		// Run the data scanner in a loop
		for {
			runDataScanner(ctx, objAPI)
			duration := time.Duration(r.Float64() * float64(scannerCycle.Load()))
			if duration < time.Second {
				// Make sure to sleep at least a second to avoid high CPU ticks.

  }

  @Test fun taskFailsWithUncheckedException() {
    queue.schedule("task", TimeUnit.MILLISECONDS.toNanos(100)) {
      log.put("failing task running")
      throw RuntimeException("boom!")
    }

    queue.schedule("task", TimeUnit.MILLISECONDS.toNanos(200)) {
      log.put("normal task running")
      return@schedule -1L
    }

    queue.idleLatch().await(500, TimeUnit.MILLISECONDS)

  protected final String escapeSlow(String s, int index) {
    int slen = s.length();

    // Get a destination buffer and setup some loop variables.
    char[] dest = Platform.charBufferFromThreadLocal();
    int destSize = dest.length;
    int destIndex = 0;
    int lastEscape = 0;

    // Loop through the rest of the string, replacing when needed into the
    // destination buffer, which gets grown as needed as well.

                break;
              } catch (CancellationException e) {
                finalResults.add(CancellationException.class);
                break;
              } catch (TimeoutException e) {
                // loop
              }
            }
            awaitUnchecked(barrier);
          }
        };
    List<Callable<?>> allTasks = new ArrayList<>();
    allTasks.add(completeSuccessfullyRunnable);

		// be extra careful: Scanner is for safe, simple jobs.
		for loop := 0; ; {
			n, err := s.r.Read(s.buf[s.end:len(s.buf)])
			if n < 0 || len(s.buf)-s.end < n {
				s.setErr(ErrBadReadCount)
				break
			}
			s.end += n
			if err != nil {
				s.setErr(err)
				break
			}
			if n > 0 {
				s.empties = 0
				break
			}
			loop++
			if loop > maxConsecutiveEmptyReads {
				s.setErr(io.ErrNoProgress)