The `TestClient` does some magic inside to call the asynchronous FastAPI application in your normal `def` test functions, using standard pytest. But that magic doesn't work anymore when we're using it inside asynchronous functions. By running our tests asynchronously, we can no longer use the `TestClient` inside our test functions.

fi

# gitconfig conditional host mount (needed for git commands inside container)
if [[ -f "${HOME}/.gitconfig" ]]; then
  CONDITIONAL_HOST_MOUNTS+="--mount type=bind,source=${HOME}/.gitconfig,destination=/home/.gitconfig,readonly "
fi

# .netrc conditional host mount (needed for git commands inside container)
if [[ -f "${HOME}/.netrc" ]]; then

<img src="/img/tutorial/body/image01.png">

And will also be used in the API docs inside each *path operation* that needs them:

<img src="/img/tutorial/body/image02.png">

## Editor support

In your editor, inside your function you will get type hints and completion everywhere (this wouldn't happen if you received a `dict` instead of a Pydantic model):

# Additional Status Codes

By default, **FastAPI** will return the responses using a `JSONResponse`, putting the content you return from your *path operation* inside of that `JSONResponse`.

It will use the default status code or the one you set in your *path operation*.

## Additional status codes

You can use `async def` or normal `def`.

And you can declare dependencies with `async def` inside of normal `def` *path operation functions*, or `def` dependencies inside of `async def` *path operation functions*, etc.

It doesn't matter. **FastAPI** will know what to do.

/// note

First, write all your **FastAPI** application as normally:

{* ../../docs_src/extending_openapi/tutorial001.py hl[1,4,7:9] *}

### Generate the OpenAPI schema

Then, use the same utility function to generate the OpenAPI schema, inside a `custom_openapi()` function:

{* ../../docs_src/extending_openapi/tutorial001.py hl[2,15:21] *}

### Modify the OpenAPI schema

And as the write operation doesn't use `async` and `await`, we define the function with normal `def`:

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

## Add the background task

Inside of your *path operation function*, pass your task function to the *background tasks* object with the method `.add_task()`:

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

`.add_task()` receives as arguments:

    return reader.lines().onClose(() -> closeUnchecked(reader));
  }

  @SuppressWarnings("Java7ApiChecker")
  @IgnoreJRERequirement // helper for lines()
  /*
   * If we make these calls inline inside the lambda inside lines(), we get an Animal Sniffer error,
   * despite the @IgnoreJRERequirement annotation there. For details, see ImmutableSortedMultiset.
   */
  private static void closeUnchecked(Closeable closeable) {
    try {

      }
    }
  }

  private static List<Object> subListCopy(Object[] source, int size) {
    final Object[] copy = new Object[size];
    arraycopy(source, 0, copy, 0, size);
    return asList(copy);
  }

  private interface IteratorOperation {
    @Nullable Object execute(Iterator<?> iterator);
  }

  /**

      }
    }
  }

  private static List<Object> subListCopy(Object[] source, int size) {
    final Object[] copy = new Object[size];
    arraycopy(source, 0, copy, 0, size);
    return asList(copy);
  }

  private interface IteratorOperation {
    @Nullable Object execute(Iterator<?> iterator);
  }

  /**