Even if your **FastAPI** application uses normal `def` functions instead of `async def`, it is still an `async` application underneath.

The `TestClient` does some magic inside to call the asynchronous FastAPI application in your normal `def` test functions, using standard pytest. But that magic doesn't work anymore when we're using it inside asynchronous functions. By running our tests asynchronously, we can no longer use the `TestClient` inside our test functions.

def magic_data_reader(raw_body: bytes):
    return {
        "size": len(raw_body),
        "content": {
            "name": "Maaaagic",
            "price": 42,
            "description": "Just kiddin', no magic here. ✨",
        },
    }


@app.post(
    "/items/",
    openapi_extra={
        "requestBody": {
            "content": {
                "application/json": {
                    "schema": {

    assert response.json() == {
        "size": 30,
        "content": {
            "name": "Maaaagic",
            "price": 42,
            "description": "Just kiddin', no magic here. ✨",
        },
    }


def test_openapi_schema():
    response = client.get("/openapi.json")
    assert response.status_code == 200, response.text
    assert response.json() == {

          }
        };
    assertEquals("foo", future.get(0, SECONDS));
  }

  public void testEvilFuture_setFuture() throws Exception {
    RuntimeException exception = new RuntimeException("you didn't say the magic word!");
    AbstractFuture<String> evilFuture =
        new AbstractFuture<String>() {
          @Override
          public void addListener(Runnable r, Executor e) {
            throw exception;
          }

          }
        };
    assertEquals("foo", future.get(0, SECONDS));
  }

  public void testEvilFuture_setFuture() throws Exception {
    RuntimeException exception = new RuntimeException("you didn't say the magic word!");
    AbstractFuture<String> evilFuture =
        new AbstractFuture<String>() {
          @Override
          public void addListener(Runnable r, Executor e) {
            throw exception;
          }

import org.codelibs.fess.util.RenderDataUtil;
import org.codelibs.fess.util.ResourceUtil;
import org.codelibs.fess.util.SearchEngineUtil;
import org.dbflute.bhv.readable.EntityRowHandler;
import org.lastaflute.core.magic.async.AsyncManager;
import org.lastaflute.web.Execute;
import org.lastaflute.web.response.ActionResponse;
import org.lastaflute.web.response.HtmlResponse;
import org.lastaflute.web.response.StreamResponse;

  cmd_path=$(command -v "${cmd}")
  if [[ ! -e "${cmd_path}" ]] ; then
    echo "${cmd} does not exist."
    exit 1
  fi
}

# Get ImageMagick command (magick for v7, convert for v6)
get_imagemagick_cmd() {
  if command -v magick >/dev/null 2>&1; then
    echo "magick"
  elif command -v convert >/dev/null 2>&1; then
    echo "convert"
  else
    echo ""
  fi
}

normale `def`-Funktionen anstelle von `async def` verwendet, handelt es sich darunter immer noch um eine `async`-Anwendung.

Der `TestClient` betreibt unter der Haube etwas Magie, um die asynchrone FastAPI-Anwendung in Ihren normalen `def`-Testfunktionen, mithilfe von Standard-Pytest aufzurufen. Aber diese Magie funktioniert nicht mehr, wenn wir sie in asynchronen Funktionen verwenden. Durch die asynchrone Ausführung unserer Tests können wir den `TestClient` nicht mehr in unseren Testfunktionen...

Incluso si tu aplicación de **FastAPI** usa funciones `def` normales en lugar de `async def`, sigue siendo una aplicación `async` por debajo.

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.