Let's look at how we can make that work.

## pytest.mark.anyio

If we want to call asynchronous functions in our tests, our test functions have to be asynchronous. AnyIO provides a neat plugin for this, that allows us to specify that some test functions are to be called asynchronously.

## HTTPX

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

   * calls returns to zero).
   *
   * Note: The time at which a [call][Call] is considered idle is different depending on whether it
   * was run [asynchronously][Call.enqueue] or [synchronously][Call.execute]. Asynchronous calls
   * become idle after the [onResponse][Callback.onResponse] or [onFailure][Callback.onFailure]
   * callback has returned. Synchronous calls become idle once [execute()][Call.execute] returns.

import com.google.common.annotations.GwtCompatible;
import java.util.concurrent.Future;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * Transforms a value, possibly asynchronously. For an example usage and more information, see
 * {@link Futures#transformAsync(ListenableFuture, AsyncFunction, Executor)}.
 *
 * @author Chris Povirk
 * @since 11.0
 */
@GwtCompatible
@FunctionalInterface

import jcifs.util.transport.Request;


/**
 * @author mbechler
 *
 */
public interface CommonServerMessageBlockRequest extends CommonServerMessageBlock, Request {

    /**
     * @return request was handled asynchronously
     */
    boolean isResponseAsync ();


    /**
     * 
     * @return next chained message
     */
    @Override
    CommonServerMessageBlockRequest getNext ();


    /**
     * 

import java.util.concurrent.Future;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A callback for accepting the results of a {@link java.util.concurrent.Future} computation
 * asynchronously.
 *
 * <p>To attach to a {@link ListenableFuture} use {@link Futures#addCallback}.
 *
 * @author Anthony Zana
 * @since 10.0
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault

   * asynchronous only if {@link CacheLoader#reload} was overridden with an asynchronous
   * implementation.
   *
   * <p>Returns without doing anything if another thread is currently loading the value for {@code
   * key}. If the cache loader associated with this cache performs refresh asynchronously then this
   * method may return before refresh completes.
   *

 *
 * All event methods must execute fast, without external locking, cannot throw exceptions,
 * attempt to mutate the event parameters, or be reentrant back into the client.
 * Any IO - writing to files or network should be done asynchronously.
 */
@ExperimentalOkHttpApi
abstract class ConnectionListener {
  /**
   * Invoked as soon as a call causes a connection to be started.
   */
  open fun connectStart(
    route: Route,
    call: Call,

 */

package com.google.common.eventbus;

import java.util.concurrent.Executor;

/**
 * An {@link EventBus} that takes the Executor of your choice and uses it to dispatch events,
 * allowing dispatch to occur asynchronously.
 *
 * @author Cliff Biffle
 * @since 10.0
 */
@ElementTypesAreNonnullByDefault
public class AsyncEventBus extends EventBus {

  /**

	v := t.val.Load()
	ttl := t.ttl
	vTime := t.lastUpdateMs.Load()
	tNow := time.Now().UnixMilli()
	if v != nil && tNow-vTime < ttl.Milliseconds() {
		return *v, nil
	}

	// Fetch new value asynchronously, while we do not return an error
	// if v != nil value or
	if t.opts.NoWait && v != nil && tNow-vTime < ttl.Milliseconds()*2 {
		if t.updating.TryLock() {
			go func() {
				defer t.updating.Unlock()

    // Already connected. Return it immediately.
    if (plan.isReady) return ConnectResult(plan)

    // Already failed? Return it immediately.
    if (plan is FailedPlan) return plan.result

    // Connect TCP asynchronously.
    tcpConnectsInFlight += plan
    val taskName = "$okHttpName connect ${routePlanner.address.url.redact()}"
    taskRunner.newQueue().schedule(
      object : Task(taskName) {