# 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:

    - name: go mod package cache
      uses: actions/cache@v4
      with:
        path: ~/go/pkg/mod
        key: ${{ runner.os }}-go-${{ matrix.go }}-${{ hashFiles('tests/go.mod') }}

    - name: Tests
      run: GITHUB_ACTION=true GORM_DIALECT=sqlite ./tests/tests_all.sh

  mysql:
    strategy:
      matrix:
        dbversion: ['mysql:9', 'mysql:8', 'mysql:5.7']
        go: ['1.23', '1.24']

{* ../../docs_src/background_tasks/tutorial001.py hl[6:9] *}

## Додавання фонової задачі

Усередині Вашої *функції обробки шляху*, передайте функцію задачі в об'єкт *background tasks*, використовуючи метод `.add_task()`:

{* ../../docs_src/background_tasks/tutorial001.py hl[14] *}

`.add_task()` приймає аргументи:

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

      "coverage" : {
        "per_day" : [ "linux" ]
      }
    } ]
  }, {
    "testId" : "org.gradle.performance.regression.corefeature.TaskAvoidancePerformanceTest.help with lazy and eager tasks",
    "groups" : [ {
      "testProject" : "largeJavaMultiProject",
      "coverage" : {
        "per_commit" : [ "linux" ]
      }
    }, {
      "testProject" : "largeMonolithicJavaProject",

      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]);
        }
      }

			newCachedAuthToken(),
			&tls.Config{
				RootCAs:          globalRootCAs,
				CipherSuites:     crypto.TLSCiphers(),
				CurvePreferences: crypto.TLSCurveIDs(),
			}),
		Local:        local,
		Hosts:        hosts,
		AuthToken:    validateStorageRequestToken,
		AuthFn:       newCachedAuthToken(),
		BlockConnect: globalGridStart,
		// Record incoming and outgoing bytes.
		Incoming:  globalConnStats.incInternodeInputBytes,

 *
 * 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