# Asynchrone Tests

Sie haben bereits gesehen, wie Sie Ihre **FastAPI**-Anwendungen mit dem bereitgestellten `TestClient` testen. Bisher haben Sie nur gesehen, wie man synchrone Tests schreibt, ohne `async`hrone Funktionen zu verwenden.

Und der Teil nach `yield` wird ausgeführt, **nachdem** die Anwendung beendet ist.

### Asynchroner Kontextmanager

Wie Sie sehen, ist die Funktion mit einem `@asynccontextmanager` versehen.

Dadurch wird die Funktion in einen sogenannten „**asynchronen Kontextmanager**“ umgewandelt.

```Python hl_lines="1  13"
{!../../../docs_src/events/tutorial003.py!}
```

):
    return value


@app.get("/synchronous-method-dependency")
async def get_synchronous_method_dependency(
    value: str = Depends(methods_dependency.synchronous),
):
    return value


@app.get("/synchronous-method-gen-dependency")
async def get_synchronous_method_gen_dependency(
    value: str = Depends(methods_dependency.synchronous_gen),
):
    return value

Calls are executed in one of two ways:

 * **Synchronous:** your thread blocks until the response is readable.

   * become idle after the [onResponse][Callback.onResponse] or [onFailure][Callback.onFailure]
   * callback has returned. Synchronous calls become idle once [execute()][Call.execute] returns.
   * This means that if you are doing synchronous calls the network layer will not truly be idle
   * until every returned [Response] has been closed.
   */
  var idleCallback: Runnable? = null

    // create options
    static final int FILE_WRITE_THROUGH           = 0x00000002;
    static final int FILE_SEQUENTIAL_ONLY         = 0x00000004;
    static final int FILE_SYNCHRONOUS_IO_ALERT    = 0x00000010;
    static final int FILE_SYNCHRONOUS_IO_NONALERT = 0x00000020;

    // security flags
    static final int SECURITY_CONTEXT_TRACKING = 0x01;
    static final int SECURITY_EFFECTIVE_ONLY   = 0x02;

    // create options
    static final int FILE_WRITE_THROUGH = 0x00000002;
    static final int FILE_SEQUENTIAL_ONLY = 0x00000004;
    static final int FILE_SYNCHRONOUS_IO_ALERT = 0x00000010;
    static final int FILE_SYNCHRONOUS_IO_NONALERT = 0x00000020;

    // security flags
    static final int SECURITY_CONTEXT_TRACKING = 0x01;
    static final int SECURITY_EFFECTIVE_ONLY = 0x02;

 * when responses are of an unexpected type or cannot be decoded.
 *
 * Other exception types cancel the current call:
 *
 *  * For synchronous calls made with [Call.execute], the exception is propagated to the caller.
 *
 *  * For asynchronous calls made with [Call.enqueue], an [IOException] is propagated to the caller

Voici un petit bout de cette histoire.

## Alternatives

Je crée des API avec des exigences complexes depuis plusieurs années (Machine Learning, systèmes distribués, jobs asynchrones, bases de données NoSQL, etc), en dirigeant plusieurs équipes de développeurs.

Dans ce cadre, j'ai dû étudier, tester et utiliser de nombreuses alternatives.

   */
  private static boolean isDeclaredThreadSafe(Method method) {
    return method.getAnnotation(AllowConcurrentEvents.class) != null;
  }

  /**
   * Subscriber that synchronizes invocations of a method to ensure that only one thread may enter
   * the method at a time.
   */
  @VisibleForTesting
  static final class SynchronizedSubscriber extends Subscriber {