/
panic_spawner.rs
57 lines (52 loc) · 1.26 KB
/
panic_spawner.rs
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use futures_task::{Spawn, SpawnError, FutureObj};
/// An implementation of [`Spawn`](futures_task::Spawn) that panics
/// when used.
///
/// # Examples
///
/// ```should_panic
/// use futures::task::SpawnExt;
/// use futures_test::task::PanicSpawner;
///
/// let mut spawn = PanicSpawner::new();
/// spawn.spawn(async { })?; // Will panic
/// # Ok::<(), Box<dyn std::error::Error>>(())
/// ```
#[derive(Debug)]
pub struct PanicSpawner {
_reserved: (),
}
impl PanicSpawner {
/// Create a new instance
pub fn new() -> Self {
Self { _reserved: () }
}
}
impl Spawn for PanicSpawner {
fn spawn_obj(
&mut self,
_future: FutureObj<'static, ()>,
) -> Result<(), SpawnError> {
panic!("should not spawn")
}
}
impl Default for PanicSpawner {
fn default() -> Self {
Self::new()
}
}
/// Get a reference to a singleton instance of [`PanicSpawner`].
///
/// # Examples
///
/// ```should_panic
/// use futures::task::SpawnExt;
/// use futures_test::task::panic_spawner_mut;
///
/// let spawner = panic_spawner_mut();
/// spawner.spawn(async { })?; // Will panic
/// # Ok::<(), Box<dyn std::error::Error>>(())
/// ```
pub fn panic_spawner_mut() -> &'static mut PanicSpawner {
Box::leak(Box::new(PanicSpawner::new()))
}