fdf_channel/
test_utils.rs

1// Copyright 2024 The Fuchsia Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5//! Helpers for writing tests involving channels.
6
7use std::cell::Cell;
8use std::sync::mpsc;
9
10/// Implements a cloneable object that will send only one message
11/// on an [`mpsc::Sender`] when its 'last' clone is dropped. It will assert
12/// if an attempt to re-clone an already cloned [`DropSender`] happens,
13/// ensuring that the object is only cloned in a linear path.
14pub struct DropSender<T: Clone>(pub T, Cell<Option<mpsc::Sender<T>>>);
15impl<T: Clone> DropSender<T> {
16    /// When this object is dropped it will send 'val' to the given 'sender'.
17    pub fn new(val: T, sender: mpsc::Sender<T>) -> Self {
18        Self(val, Cell::new(Some(sender)))
19    }
20}
21impl<T: Clone> Drop for DropSender<T> {
22    fn drop(&mut self) {
23        match self.1.get_mut() {
24            Some(sender) => {
25                println!("dropping a drop sender");
26                sender.send(self.0.clone()).unwrap();
27            }
28            _ => {}
29        }
30    }
31}
32impl<T: Clone> Clone for DropSender<T> {
33    fn clone(&self) -> Self {
34        Self(
35            self.0.clone(),
36            Cell::new(Some(self.1.take().expect("Attempted to re-clone a `DropSender`"))),
37        )
38    }
39}
fdf_channel/test_utils.rs

fdf_channel/
test_utils.rs
