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.

import org.dbflute.mail.send.supplement.label.SMailLabelStrategy;
import org.dbflute.optional.OptionalThing;
import org.dbflute.util.DfStringUtil;
import org.lastaflute.core.magic.async.AsyncManager;
import org.lastaflute.core.magic.async.ConcurrentAsyncCall;
import org.lastaflute.core.message.MessageManager;
import org.lastaflute.core.util.ContainerUtil;

/**
 * @author jflute
 */

    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() == {

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": {

# Treat all files in the Go repo as binary, with no git magic updating
# line endings. This produces predictable results in different environments.
#
# Windows users contributing to Go will need to use a modern version
# of git and editors capable of LF line endings.
#
# Windows .bat files are known to have multiple bugs when run with LF
# endings, and so they are checked in with CRLF endings, with a test

	return nil
}

// fakeNs is a mock struct for testing
type fakeNs struct {
	closed *atomic.Bool
	fd     uintptr
	inode  uint64
}

func newFakeNs(fd uintptr) *fakeNs {
	// the fake inode is the fd! magic.
	return &fakeNs{closed: &atomic.Bool{}, fd: fd, inode: uint64(fd)}
}

func newFakeNsInode(fd uintptr, inode uint64) *fakeNs {
	return &fakeNs{closed: &atomic.Bool{}, fd: fd, inode: inode}
}

import org.codelibs.fess.sso.SsoAuthenticator;
import org.codelibs.fess.util.ComponentUtil;
import org.dbflute.optional.OptionalEntity;
import org.dbflute.optional.OptionalThing;
import org.lastaflute.core.magic.async.AsyncManager;
import org.lastaflute.core.time.TimeManager;
import org.lastaflute.web.login.LoginHandlingResource;
import org.lastaflute.web.login.PrimaryLoginManager;
import org.lastaflute.web.login.TypicalLoginAssist;

 * limitations under the License.
 */
package okhttp3.internal.ws

import okio.Buffer
import okio.ByteString.Companion.encodeUtf8

object WebSocketProtocol {
  /** Magic value which must be appended to the key in a response header. */
  internal const val ACCEPT_MAGIC = "258EAFA5-E914-47DA-95CA-C5AB0DC85B11"

  /*
  Each frame starts with two bytes of data.

	"github.com/minio/highwayhash"
	"github.com/minio/minio/internal/hash/sha256"
	"golang.org/x/crypto/blake2b"

	xioutil "github.com/minio/minio/internal/ioutil"
	"github.com/minio/minio/internal/logger"
)

// magic HH-256 key as HH-256 hash of the first 100 decimals of π as utf-8 string with a zero key.

  set arg1=%~1
  if "!arg1:~0,2!"=="-D" (
   	set "args=%args% "%~1"="%~2""
    shift
    shift
    goto argsloop
  )

  if "%~1"=="-jvm-debug" (
    if not "%~2"=="" (
      rem This piece of magic somehow checks that an argument is a number
      for /F "delims=0123456789" %%i in ("%~2") do (
        set var="%%i"
      )
      if defined var (
        rem Not a number, assume no argument given and default to 9999