# CORS (Cross-Origin Resource Sharing) { #cors-cross-origin-resource-sharing }

<a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS" class="external-link" target="_blank">CORS o "Cross-Origin Resource Sharing"</a> se refiere a situaciones en las que un frontend que se ejecuta en un navegador tiene código JavaScript que se comunica con un backend, y el backend está en un "origen" diferente al frontend.

## Origen { #origin }

`TestClient` 在内部通过一些“魔法”操作，使得您可以在普通的 `def` 测试函数中调用异步的 FastAPI 应用程序，并使用标准的 pytest。但当我们在异步函数中使用它时，这种“魔法”就不再生效了。由于测试以异步方式运行，我们无法在测试函数中继续使用 `TestClient`。

`TestClient` 是基于 <a href="https://www.python-httpx.org" class="external-link" target="_blank">HTTPX</a> 的。幸运的是，我们可以直接使用它来测试API。

## 示例

# Without aliases


@app.get("/required-str")
async def read_required_str(p: Annotated[str, Header()]):
    return {"p": p}


class HeaderModelRequiredStr(BaseModel):
    p: str


@app.get("/model-required-str")
async def read_model_required_str(p: Annotated[HeaderModelRequiredStr, Header()]):
    return {"p": p.p}

 * Duplicate host settings help prevent indexing the same content from multiple similar URLs.
 *
 */
public class ApiAdminDuplicatehostAction extends FessApiAdminAction {

    private static final Logger logger = LogManager.getLogger(ApiAdminDuplicatehostAction.class);

    // ===================================================================================

import org.junit.jupiter.api.DisplayName;
import org.junit.jupiter.api.Test;

/**
 * Unit tests for SmbComTransaction class
 */
class SmbComTransactionTest {

    private TestSmbComTransaction transaction;

    // Test implementation of abstract SmbComTransaction
    static class TestSmbComTransaction extends SmbComTransaction {

        private int setupBytesWritten = 2;
        private int parameterBytesWritten = 20;

/**
 * TODO: this is session scoped as SPI can contribute.
 */
@Named
@Singleton
public class DefaultPackagingRegistry
        extends ExtensibleEnumRegistries.DefaultExtensibleEnumRegistry<Packaging, PackagingProvider>
        implements PackagingRegistry {

    private static final Logger LOGGER = LoggerFactory.getLogger(DefaultPackagingRegistry.class);

    private final Lookup lookup;

    private final TypeRegistry typeRegistry;

        ArrayList<ProducedArtifact> result = new ArrayList<>(2);
        result.add(session.getArtifact(ProducedArtifact.class, pomArtifact));
        if (!ArtifactIdUtils.equalsVersionlessId(pomArtifact, projectArtifact)) {
            result.add(session.getArtifact(ProducedArtifact.class, projectArtifact));
        }
        return Collections.unmodifiableList(result);
    }

    @Nonnull
    @Override

<div class="termy">

```console
$ pip install "fastapi[standard]"

---> 100%
```

</div>

/// note | Nota

Quando você instala com `pip install "fastapi[standard]"`, ele vem com algumas dependências opcionais padrão, incluindo `fastapi-cloud-cli`, que permite fazer deploy na <a href="https://fastapicloud.com" class="external-link" target="_blank">FastAPI Cloud</a>.

 * @author Gregory Kick
 */
@GwtCompatible
abstract class RegularImmutableTable<R, C, V> extends ImmutableTable<R, C, V> {
  RegularImmutableTable() {}

  abstract Cell<R, C, V> getCell(int iterationIndex);

  @Override
  final ImmutableSet<Cell<R, C, V>> createCellSet() {
    return isEmpty() ? ImmutableSet.of() : new CellSet();
  }

  @WeakOuter
  private final class CellSet extends IndexedImmutableSet<Cell<R, C, V>> {

/**
 * Base class for services that can implement {@link #startUp}, {@link #run} and {@link #shutDown}
 * methods. This class uses a single thread to execute the service; consider {@link AbstractService}
 * if you would like to manage any threading manually.
 *
 * @author Jesse Wilson
 * @since 1.0
 */
@GwtIncompatible
@J2ktIncompatible
public abstract class AbstractExecutionThreadService implements Service {