assert response.status_code == 200, response.text
    assert response.json() == {"message": "No file sent"}


def test_post_uploadfile_no_body():
    response = client.post("/uploadfile/")
    assert response.status_code == 200, response.text
    assert response.json() == {"message": "No upload file sent"}


def test_post_file(tmp_path):
    path = tmp_path / "test.txt"
    path.write_bytes(b"<file content>")

    assert response.status_code == 200, response.text
    assert response.json() == {"message": "No file sent"}


@needs_py310
def test_post_uploadfile_no_body(client: TestClient):
    response = client.post("/uploadfile/")
    assert response.status_code == 200, response.text
    assert response.json() == {"message": "No upload file sent"}


@needs_py310
def test_post_file(tmp_path: Path, client: TestClient):

	// Buffers sent on out can not be referenced once sent.
	StreamHandlerFn func(ctx context.Context, payload []byte, in <-chan []byte, out chan<- []byte) *RemoteErr

	// StreamHandler handles fully bidirectional streams,
	// There is flow control in both directions.
	StreamHandler struct {
		// Handle an incoming request. Initial payload is sent.

	responses <-chan Response
	cancel    context.CancelCauseFunc

	// Requests sent to the server.
	// If the handler is defined with 0 incoming capacity this will be nil.
	// Channel *must* be closed to signal the end of the stream.
	// If the request context is canceled, the stream will no longer process requests.
	// Requests sent cannot be used any further by the called.
	Requests chan<- []byte

	muxID uint64

// It does not encrypt empty ETags because such ETags indicate
// that the S3 client hasn't sent an ETag = MD5(object) and
// the backend can pick an ETag value.
func (key ObjectKey) SealETag(etag []byte) []byte {
	if len(etag) == 0 { // don't encrypt empty ETag - only if client sent ETag = MD5(object)
		return etag
	}
	var buffer bytes.Buffer
	mac := hmac.New(sha256.New, key[:])

You can declare a parameter in a *path operation function* or dependency function with the type `BackgroundTasks`, and then you can use it to schedule the execution of background tasks after the response is sent.

You can import it directly from `fastapi`:

```python
from fastapi import BackgroundTasks
```

    Note over client,operation: Response is already sent, can't change it anymore
    opt Tasks
        operation -->> tasks: Send background tasks
    end
    opt Raise other exception
        tasks -->> tasks: Handle exceptions in the background task code
    end
```

/// info

        os.remove(log)  # pragma: no cover
    response = client.post("/send-notification/******@****.***")
    assert response.status_code == 200, response.text
    assert response.json() == {"message": "Notification sent in the background"}
    with open("./log.txt") as f:

        os.remove(log)  # pragma: no cover
    response = client.post("/send-notification/******@****.***?q=some-query")
    assert response.status_code == 200, response.text
    assert response.json() == {"message": "Message sent"}
    with open("./log.txt") as f:

    email: str, background_tasks: BackgroundTasks, q: Annotated[str, Depends(get_query)]
):
    message = f"message to {email}\n"
    background_tasks.add_task(write_log, message)