Digamos que tienes una estructura de archivos como se describe en [Aplicaciones Más Grandes](bigger-applications.md){.internal-link target=_blank}:

```
.
├── app
│   ├── __init__.py
│   └── main.py
```

En el archivo `main.py` tienes tu aplicación de **FastAPI**:

{* ../../docs_src/app_testing/app_a_py39/main.py *}

### Archivo de prueba { #testing-file }

        long epochFiletime = 116444736000000000L;
        writeLittleEndianLong(dos, epochFiletime);

        ByteArrayInputStream bais = new ByteArrayInputStream(baos.toByteArray());
        PacDataInputStream pacStream = new PacDataInputStream(bais);

        Date date = pacStream.readFiletime();
        assertNotNull(date);
        // The date should be around 1970 (allowing for some conversion differences)

```
.
├── app
│   ├── __init__.py
│   └── main.py
```

In der Datei `main.py` haben Sie Ihre **FastAPI**-Anwendung:


{* ../../docs_src/app_testing/app_a_py39/main.py *}


### Testdatei { #testing-file }

    assertTrue(entries.contains(Maps.<String, @Nullable Boolean>immutableEntry("b", null)));
    assertTrue(
        entries.contains(Maps.<@Nullable String, @Nullable Boolean>immutableEntry(null, null)));

    assertFalse(entries.contains(Maps.<String, @Nullable Boolean>immutableEntry("c", null)));
    assertFalse(entries.contains(Maps.<@Nullable String, Boolean>immutableEntry(null, true)));
  }

/**
 * An object representing the differences between two maps.
 *
 * @author Kevin Bourrillion
 * @since 2.0
 */
@DoNotMock("Use Maps.difference")
@GwtCompatible
public interface MapDifference<K extends @Nullable Object, V extends @Nullable Object> {
  /**
   * Returns {@code true} if there are no differences between the two maps; that is, if the maps are
   * equal.
   */
  boolean areEqual();

  /**

import jakarta.mail.Address;
import jakarta.mail.BodyPart;
import jakarta.mail.Header;
import jakarta.mail.Message;
import jakarta.mail.MessagingException;
import jakarta.mail.Multipart;
import jakarta.mail.Part;
import jakarta.mail.Session;
import jakarta.mail.internet.MailDateFormat;
import jakarta.mail.internet.MimeMessage;
import jakarta.mail.internet.MimeUtility;

/**

///

## The main `FastAPI` { #the-main-fastapi }

Now, let's see the module at `app/main.py`.

Here's where you import and use the class `FastAPI`.

This will be the main file in your application that ties everything together.

And as most of your logic will now live in its own specific module, the main file will be quite simple.

### Import `FastAPI` { #import-fastapi }

```
.
├── app
│   ├── __init__.py
│   └── main.py
```

В файле `main.py` находится Ваше приложение **FastAPI**:


{* ../../docs_src/app_testing/app_a_py39/main.py *}

### Файл тестов { #testing-file }

.
├── app
│   ├── __init__.py
│   └── main.py
```

在 `main.py` 文件中你有一个 **FastAPI** app:


{* ../../docs_src/app_testing/main.py *}

### 测试文件

然后你会有一个包含测试的文件 `test_main.py` 。app可以像Python包那样存在（一样是目录，但有个 `__init__.py` 文件）：

``` hl_lines="5"
.
├── app
│   ├── __init__.py
│   ├── main.py
│   └── test_main.py
```

因为这文件在同一个包中，所以你可以通过相对导入从 `main` 模块（`main.py`）导入`app`对象：

因此，为了能够在同一个文件中使用它们，我们直接导入子模块：

```Python hl_lines="5" title="app/main.py"
{!../../docs_src/bigger_applications/app/main.py!}
```

### 包含 `users` 和 `items` 的 `APIRouter`

现在，让我们来包含来自 `users` 和 `items` 子模块的 `router`。

```Python hl_lines="10-11" title="app/main.py"
{!../../docs_src/bigger_applications/app/main.py!}
```

/// info

`users.router` 包含了 `app/routers/users.py` 文件中的 `APIRouter`。