O `TestClient` faz algumas mágicas para invocar a aplicação FastAPI assíncrona em suas funções `def` normais, utilizando o pytest padrão. Porém a mágica não acontece mais quando nós estamos utilizando dentro de funções assíncronas. Ao executar os nossos testes de forma assíncrona, nós não podemos mais utilizar o `TestClient` dentro das nossas funções de teste.

{* ../../docs_src/background_tasks/tutorial001.py hl[1,13] *}

**FastAPI** créera l'objet de type `BackgroundTasks` pour vous et le passera comme paramètre.

## Créer une fonction de tâche

Une fonction à exécuter comme tâche d'arrière-plan est juste une fonction standard qui peut recevoir des paramètres.

Elle peut être une fonction asynchrone (`async def`) ou une fonction normale (`def`), **FastAPI** saura la gérer correctement.

        new Service() {
          final NoOpService delegate = new NoOpService();

          @Override
          public final void addListener(Listener listener, Executor executor) {
            service1.startAsync();
            delegate.addListener(listener, executor);
          }

          // Delegates from here on down
          @Override
          public final Service startAsync() {

import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.ConcurrentNavigableMap;
import java.util.concurrent.ConcurrentSkipListMap;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.Executor;
import java.util.concurrent.LinkedBlockingDeque;
import java.util.concurrent.ScheduledThreadPoolExecutor;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.ThreadPoolExecutor;

De cette façon, vous n'avez pas à "installer" votre version locale pour pouvoir tester chaque changement.

### Formatage

Il existe un script que vous pouvez exécuter qui formatera et nettoiera tout votre code :

<div class="termy">

```console
$ bash scripts/format.sh
```

</div>

Il effectuera également un tri automatique de touts vos imports.

### Deletar um Hero

Também podemos **deletar** um `Hero`.

{* ../../docs_src/sql_databases/tutorial001_an_py310.py ln[66:73] hl[71] *}

### Executar o App

Você pode executar o app:

<div class="termy">

```console
$ fastapi dev main.py

<span style="color: green;">INFO</span>:     Uvicorn running on http://127.0.0.1:8000 (Press CTRL+C to quit)
```

      get() = originalRequest

    val call: RealCall
      get() = this@RealCall

    /**
     * Attempt to enqueue this async call on [executorService]. This will attempt to clean up
     * if the executor has been shut down by reporting the call as failed.
     */
    fun executeOn(executorService: ExecutorService) {
      client.dispatcher.assertThreadDoesntHoldLock()

      var success = false
      try {

    server.enqueue(MockResponse(body = "A"))
    server.enqueue(MockResponse(body = "A"))
    val executor = Executors.newCachedThreadPool(threadFactory("HttpOverHttp2Test"))
    val countDownLatch = CountDownLatch(2)
    executor.execute(AsyncRequest("/r1", countDownLatch))
    executor.execute(AsyncRequest("/r2", countDownLatch))
    countDownLatch.await()
    assertThat(server.takeRequest().sequenceNumber).isEqualTo(0)

        .connectionPool(
          buildConnectionPool(
            connectionListener = connectionListener,
            taskRunner = taskRunner,
          ),
        )
        .dispatcher(Dispatcher(backend.executor))
        .taskRunnerInternal(taskRunner)
    } else {
      OkHttpClient.Builder()
        .connectionPool(ConnectionPool(connectionListener = connectionListener))
    }

import java.io.IOException
import java.net.HttpURLConnection
import java.net.ProtocolException
import java.util.concurrent.BlockingQueue
import java.util.concurrent.CountDownLatch
import java.util.concurrent.Executors
import java.util.concurrent.LinkedBlockingQueue
import java.util.concurrent.TimeUnit
import kotlin.test.assertFailsWith
import mockwebserver3.MockResponse
import mockwebserver3.MockWebServer