# Async Tests { #async-tests }

You have already seen how to test your **FastAPI** applications using the provided `TestClient`. Up to now, you have only seen how to write synchronous tests, without using `async` functions.

# Background Tasks { #background-tasks }

You can define background tasks to be run *after* returning a response.

This is useful for operations that need to happen after a request, but that the client doesn't really have to be waiting for the operation to complete before receiving the response.

This includes, for example:

* Email notifications sent after performing an action:

Klaus Post <******@****.***> 1756435188 +0200

      return new SampleElements<>(
          mapEntry("foo", 5),
          mapEntry("bar", 3),
          mapEntry("baz", 17),
          mapEntry("quux", 1),
          mapEntry("toaster", -2));
    }

    @SuppressWarnings("unchecked")
    @Override
    public Entry<String, Integer>[] createArray(int length) {
      return (Entry<String, Integer>[]) new Entry<?, ?>[length];
    }

        Type[] toArgs = toParameterizedType.getActualTypeArguments();
        checkArgument(
            fromArgs.length == toArgs.length,
            "%s not compatible with %s",
            fromParameterizedType,
            toParameterizedType);
        for (int i = 0; i < fromArgs.length; i++) {
          populateTypeMappings(mappings, fromArgs[i], toArgs[i]);
        }
      }

 *
 * This class provides helper methods for working with ASN.1
 * encoded data structures used in Kerberos PAC processing.
 */
public final class ASN1Util {

    private ASN1Util() {
    }

    /**
     * Casts an object to the specified type with type checking
     * @param <T> the target type
     * @param type the target class type
     * @param object the object to cast
     * @return object cast to type

    "bucket": "testbucket",
    "object": "hosts",
    "status": "OK",
    "statusCode": 200,
    "rx": 401,
    "tx": 0,
    "timeToResponse": "13309747ns",
    "timeToResponseInNS": "13309747"
  },
  "remotehost": "127.0.0.1",
  "requestID": "17CDC1F4D7E69123",
  "userAgent": "MinIO (linux; amd64) minio-go/v7.0.70 mc/RELEASE.2024-04-30T17-44-48Z",
  "requestPath": "/testbucket/hosts",
  "requestHost": "localhost:9000",

     * This is a special name that means all hosts. If you wish to find all hosts
     * on a network querying a workgroup group name is the preferred method.
     */

    static final String ANY_HOSTS_NAME = "*\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000\u0000";

    /**
     * This is a special name for querying the master browser that serves the
     * list of hosts found in "Network Neighborhood".
     */

import javax.net.ssl.SSLEngine
import javax.net.ssl.X509ExtendedTrustManager
import org.codehaus.mojo.animal_sniffer.IgnoreJRERequirement

/**
 * This extends [X509ExtendedTrustManager] to disable verification for a set of hosts.
 *
 * Note that the superclass [X509ExtendedTrustManager] isn't available on Android until version 7
 * (API level 24).
 */
@IgnoreJRERequirement
internal class InsecureExtendedTrustManager(

            final String toStrs = fessConfig.getNotificationTo();
            final Postbox postbox = ComponentUtil.getComponent(Postbox.class);
            try {
                final String[] toAddresses;
                if (StringUtil.isNotBlank(toStrs)) {
                    toAddresses = toStrs.split(",");
                } else {