* <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/X-Forwarded-Proto" class="external-link" target="_blank">X-Forwarded-Proto</a>
* <a href="https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/X-Forwarded-Host" class="external-link" target="_blank">X-Forwarded-Host</a>

///

# История, проектирование и будущее { #history-design-and-future }

Однажды, <a href="https://github.com/fastapi/fastapi/issues/3#issuecomment-454956920" class="external-link" target="_blank">один из пользователей **FastAPI** задал вопрос</a>:

> Какова история этого проекта? Создаётся впечатление, что он явился из ниоткуда и завоевал мир за несколько недель [...]

Что ж, вот небольшая часть истории проекта.

## Альтернативы { #alternatives }

* <a href="https://github.com/florimondmanca/msgpack-asgi" class="external-link" target="_blank">MessagePack</a>

/**
 */
@Deprecated
public interface EventDispatcher {

    void addEventMonitor(EventMonitor monitor);

    void dispatchStart(String event, String target);

    void dispatchEnd(String event, String target);

    void dispatchError(String event, String target, Throwable cause);

En ese caso, se aplicarán a todas las *path operations* en la aplicación:

{* ../../docs_src/dependencies/tutorial012_an_py39.py hl[17] *}

# 测试

感谢 <a href="https://www.starlette.dev/testclient/" class="external-link" target="_blank">Starlette</a>，测试**FastAPI** 应用轻松又愉快。

它基于 <a href="https://www.python-httpx.org" class="external-link" target="_blank">HTTPX</a>， 而HTTPX又是基于Requests设计的，所以很相似且易懂。

有了它，你可以直接与**FastAPI**一起使用 <a href="https://docs.pytest.org/" class="external-link" target="_blank">pytest</a>。

## 使用 `TestClient`

/// info | 信息

Именно поэтому, **FastAPI** сам предоставляет альтернативную документацию API (используя ReDoc), которую можно получить по адресу: <a href="http://127.0.0.1:8000/redoc" class="external-link" target="_blank">http://127.0.0.1:8000/redoc</a>.

<img src="/img/tutorial/path-params/image02.png">

///

## Use cases { #use-cases }

Some use cases include:

* Converting non-JSON request bodies to JSON (e.g. <a href="https://msgpack.org/index.html" class="external-link" target="_blank">`msgpack`</a>).
* Decompressing gzip-compressed request bodies.
* Automatically logging all request bodies.

## Handling custom request body encodings { #handling-custom-request-body-encodings }

/**
 * Unit test for {@link AppendableWriter}.
 *
 * @author Alan Green
 */
@NullUnmarked
public class AppendableWriterTest extends IoTestCase {

  /** Helper class for testing behavior with Flushable and Closeable targets. */
  private static class SpyAppendable implements Appendable, Flushable, Closeable {
    boolean flushed;
    boolean closed;
    final StringBuilder result = new StringBuilder();

    @Override

## Conclusão { #conclusion }

Com isso, você deve ter uma compreensão básica do que são **variáveis ​​de ambiente** e como usá-las em Python.

Você também pode ler mais sobre elas na <a href="https://en.wikipedia.org/wiki/Environment_variable" class="external-link" target="_blank">Wikipedia para Variáveis ​​de Ambiente</a>.