1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
//! Futures compatibility for [`tracing`].
//!
//! # Overview
//!
//! [`tracing`] is a framework for instrumenting Rust programs to collect
//! structured, event-based diagnostic information. This crate provides utilities
//! for using `tracing` to instrument asynchronous code written using futures and
//! async/await.
//!
//! The crate provides the following traits:
//!
//! * [`Instrument`] allows a `tracing` [span] to be attached to a future, sink,
//!   stream, or executor.
//!
//! * [`WithSubscriber`] allows a `tracing` [`Subscriber`] to be attached to a
//!   future, sink, stream, or executor.
//!
//! # Feature flags
//!
//! This crate provides a number of feature flags that enable compatibility
//! features with other crates in the asynchronous ecosystem:
//!
//! - `tokio`: Enables compatibility with the `tokio` crate, including
//!    [`Instrument`] and [`WithSubscriber`] implementations for
//!    `tokio::executor::Executor`, `tokio::runtime::Runtime`, and
//!    `tokio::runtime::current_thread`. Enabled by default.
//! - `tokio-executor`: Enables compatibility with the `tokio-executor`
//!    crate, including  [`Instrument`] and [`WithSubscriber`]
//!    implementations for types implementing `tokio_executor::Executor`.
//!    This is intended primarily for use in crates which depend on
//!    `tokio-executor` rather than `tokio`; in general the `tokio` feature
//!    should be used instead.
//! - `std-future`: Enables compatibility with `std::future::Future`.
//! - `futures-01`: Enables compatibility with version 0.1.x of the [`futures`]
//!   crate.
//! - `futures-03`: Enables compatibility with version 0.3.x of the `futures`
//!   crate's `Spawn` and `LocalSpawn` traits.
//! - `tokio-alpha`: Enables compatibility with `tokio` 0.2's alpha releases,
//!   including the `tokio` 0.2 `Executor` and `TypedExecutor` traits.
//! - `std`: Depend on the Rust standard library.
//!
//!   `no_std` users may disable this feature with `default-features = false`:
//!
//!   ```toml
//!   [dependencies]
//!   tracing-futures = { version = "0.2.3", default-features = false }
//!   ```
//!
//! The `tokio`, `std-future` and `std` features are enabled by default.
//!
//! [`tracing`]: https://crates.io/crates/tracing
//! [span]: https://docs.rs/tracing/latest/tracing/span/index.html
//! [`Subscriber`]: https://docs.rs/tracing/latest/tracing/subscriber/index.html
//! [`Instrument`]: trait.Instrument.html
//! [`WithSubscriber`]: trait.WithSubscriber.html
//! [`futures`]: https://crates.io/crates/futures
#![doc(html_root_url = "https://docs.rs/tracing-futures/0.2.3")]
#![warn(
    missing_debug_implementations,
    missing_docs,
    rust_2018_idioms,
    unreachable_pub,
    bad_style,
    const_err,
    dead_code,
    improper_ctypes,
    non_shorthand_field_patterns,
    no_mangle_generic_items,
    overflowing_literals,
    path_statements,
    patterns_in_fns_without_body,
    private_in_public,
    unconditional_recursion,
    unused,
    unused_allocation,
    unused_comparisons,
    unused_parens,
    while_true
)]
#![cfg_attr(not(feature = "std"), no_std)]
#![cfg_attr(docsrs, feature(doc_cfg))]
#[cfg(feature = "std-future")]
use pin_project::pin_project;

pub(crate) mod stdlib;

#[cfg(feature = "std-future")]
use crate::stdlib::{pin::Pin, task::Context};

use tracing::dispatcher;
use tracing::{Dispatch, Span};

/// Implementations for `Instrument`ed future executors.
pub mod executor;

/// Extension trait allowing futures, streams, sinks, and executors to be
/// instrumented with a `tracing` [span].
///
/// [span]: https://docs.rs/tracing/latest/tracing/span/index.html
pub trait Instrument: Sized {
    /// Instruments this type with the provided `Span`, returning an
    /// `Instrumented` wrapper.
    ///
    /// If the instrumented type is a future, stream, or sink, the attached `Span`
    /// will be [entered] every time it is polled. If the instrumented type
    /// is a future executor, every future spawned on that executor will be
    /// instrumented by the attached `Span`.
    ///
    /// # Examples
    ///
    /// Instrumenting a future:
    ///
    // TODO: ignored until async-await is stable...
    /// ```rust,ignore
    /// use tracing_futures::Instrument;
    ///
    /// # async fn doc() {
    /// let my_future = async {
    ///     // ...
    /// };
    ///
    /// my_future
    ///     .instrument(tracing::info_span!("my_future"))
    ///     .await
    /// # }
    /// ```
    ///
    /// [entered]: https://docs.rs/tracing/latest/tracing/span/struct.Span.html#method.enter
    fn instrument(self, span: Span) -> Instrumented<Self> {
        Instrumented { inner: self, span }
    }

    /// Instruments this type with the [current] `Span`, returning an
    /// `Instrumented` wrapper.
    ///
    /// If the instrumented type is a future, stream, or sink, the attached `Span`
    /// will be [entered] every time it is polled. If the instrumented type
    /// is a future executor, every future spawned on that executor will be
    /// instrumented by the attached `Span`.
    ///
    /// This can be used to propagate the current span when spawning a new future.
    ///
    /// # Examples
    ///
    // TODO: ignored until async-await is stable...
    /// ```rust,ignore
    /// use tracing_futures::Instrument;
    ///
    /// # async fn doc() {
    /// let span = tracing::info_span!("my_span");
    /// let _enter = span.enter();
    ///
    /// // ...
    ///
    /// let future = async {
    ///     tracing::debug!("this event will occur inside `my_span`");
    ///     // ...
    /// };
    /// tokio::spawn(future.in_current_span());
    /// # }
    /// ```
    ///
    /// [current]: https://docs.rs/tracing/latest/tracing/span/struct.Span.html#method.current
    /// [entered]: https://docs.rs/tracing/latest/tracing/span/struct.Span.html#method.enter
    #[inline]
    fn in_current_span(self) -> Instrumented<Self> {
        self.instrument(Span::current())
    }
}

/// Extension trait allowing futures, streams, and sinks to be instrumented with
/// a `tracing` [`Subscriber`].
///
/// [`Subscriber`]: https://docs.rs/tracing/latest/tracing/subscriber/trait.Subscriber.html
#[cfg(feature = "std")]
#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
pub trait WithSubscriber: Sized {
    /// Attaches the provided [`Subscriber`] to this type, returning a
    /// `WithDispatch` wrapper.
    ///
    /// When the wrapped type is a future, stream, or sink, the attached
    /// subscriber will be set as the [default] while it is being polled.
    /// When the wrapped type is an executor, the subscriber will be set as the
    /// default for any futures spawned on that executor.
    ///
    /// [`Subscriber`]: https://docs.rs/tracing/latest/tracing/subscriber/trait.Subscriber.html
    /// [default]: https://docs.rs/tracing/latest/tracing/dispatcher/index.html#setting-the-default-subscriber
    fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self>
    where
        S: Into<Dispatch>,
    {
        WithDispatch {
            inner: self,
            dispatch: subscriber.into(),
        }
    }

    /// Attaches the current [default] [`Subscriber`] to this type, returning a
    /// `WithDispatch` wrapper.
    ///
    /// When the wrapped type is a future, stream, or sink, the attached
    /// subscriber will be set as the [default] while it is being polled.
    /// When the wrapped type is an executor, the subscriber will be set as the
    /// default for any futures spawned on that executor.
    ///
    /// This can be used to propagate the current dispatcher context when
    /// spawning a new future.
    ///
    /// [`Subscriber`]: https://docs.rs/tracing/latest/tracing/subscriber/trait.Subscriber.html
    /// [default]: https://docs.rs/tracing/latest/tracing/dispatcher/index.html#setting-the-default-subscriber
    #[inline]
    fn with_current_subscriber(self) -> WithDispatch<Self> {
        WithDispatch {
            inner: self,
            dispatch: dispatcher::get_default(|default| default.clone()),
        }
    }
}

/// A future, stream, sink, or executor that has been instrumented with a `tracing` span.
#[cfg_attr(feature = "std-future", pin_project)]
#[derive(Debug, Clone)]
pub struct Instrumented<T> {
    #[cfg(feature = "std-future")]
    #[pin]
    inner: T,
    #[cfg(not(feature = "std-future"))]
    inner: T,
    span: Span,
}

/// A future, stream, sink, or executor that has been instrumented with a
/// `tracing` subscriber.
#[cfg(feature = "std")]
#[cfg_attr(docsrs, doc(cfg(feature = "std")))]
#[cfg_attr(feature = "std-future", pin_project)]
#[derive(Clone, Debug)]
pub struct WithDispatch<T> {
    // cfg_attr doesn't work inside structs, apparently...
    #[cfg(feature = "std-future")]
    #[pin]
    inner: T,
    #[cfg(not(feature = "std-future"))]
    inner: T,
    dispatch: Dispatch,
}

impl<T: Sized> Instrument for T {}

#[cfg(feature = "std-future")]
#[cfg_attr(docsrs, doc(cfg(feature = "std-future")))]
impl<T: crate::stdlib::future::Future> crate::stdlib::future::Future for Instrumented<T> {
    type Output = T::Output;

    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> crate::stdlib::task::Poll<Self::Output> {
        let this = self.project();
        let _enter = this.span.enter();
        this.inner.poll(cx)
    }
}

#[cfg(feature = "futures-01")]
#[cfg_attr(docsrs, doc(cfg(feature = "futures-01")))]
impl<T: futures_01::Future> futures_01::Future for Instrumented<T> {
    type Item = T::Item;
    type Error = T::Error;

    fn poll(&mut self) -> futures_01::Poll<Self::Item, Self::Error> {
        let _enter = self.span.enter();
        self.inner.poll()
    }
}

#[cfg(feature = "futures-01")]
#[cfg_attr(docsrs, doc(cfg(feature = "futures-01")))]
impl<T: futures_01::Stream> futures_01::Stream for Instrumented<T> {
    type Item = T::Item;
    type Error = T::Error;

    fn poll(&mut self) -> futures_01::Poll<Option<Self::Item>, Self::Error> {
        let _enter = self.span.enter();
        self.inner.poll()
    }
}

#[cfg(feature = "futures-01")]
#[cfg_attr(docsrs, doc(cfg(feature = "futures-01")))]
impl<T: futures_01::Sink> futures_01::Sink for Instrumented<T> {
    type SinkItem = T::SinkItem;
    type SinkError = T::SinkError;

    fn start_send(
        &mut self,
        item: Self::SinkItem,
    ) -> futures_01::StartSend<Self::SinkItem, Self::SinkError> {
        let _enter = self.span.enter();
        self.inner.start_send(item)
    }

    fn poll_complete(&mut self) -> futures_01::Poll<(), Self::SinkError> {
        let _enter = self.span.enter();
        self.inner.poll_complete()
    }
}

#[cfg(all(feature = "futures-03", feature = "std-future"))]
#[cfg_attr(docsrs, doc(cfg(all(feature = "futures-03", feature = "std-future"))))]
impl<T: futures::Stream> futures::Stream for Instrumented<T> {
    type Item = T::Item;

    fn poll_next(
        self: Pin<&mut Self>,
        cx: &mut Context<'_>,
    ) -> futures::task::Poll<Option<Self::Item>> {
        let this = self.project();
        let _enter = this.span.enter();
        T::poll_next(this.inner, cx)
    }
}

#[cfg(all(feature = "futures-03", feature = "std-future"))]
#[cfg_attr(docsrs, doc(cfg(all(feature = "futures-03", feature = "std-future"))))]
impl<I, T: futures::Sink<I>> futures::Sink<I> for Instrumented<T>
where
    T: futures::Sink<I>,
{
    type Error = T::Error;

    fn poll_ready(
        self: Pin<&mut Self>,
        cx: &mut Context<'_>,
    ) -> futures::task::Poll<Result<(), Self::Error>> {
        let this = self.project();
        let _enter = this.span.enter();
        T::poll_ready(this.inner, cx)
    }

    fn start_send(self: Pin<&mut Self>, item: I) -> Result<(), Self::Error> {
        let this = self.project();
        let _enter = this.span.enter();
        T::start_send(this.inner, item)
    }

    fn poll_flush(
        self: Pin<&mut Self>,
        cx: &mut Context<'_>,
    ) -> futures::task::Poll<Result<(), Self::Error>> {
        let this = self.project();
        let _enter = this.span.enter();
        T::poll_flush(this.inner, cx)
    }

    fn poll_close(
        self: Pin<&mut Self>,
        cx: &mut Context<'_>,
    ) -> futures::task::Poll<Result<(), Self::Error>> {
        let this = self.project();
        let _enter = this.span.enter();
        T::poll_close(this.inner, cx)
    }
}

impl<T> Instrumented<T> {
    /// Borrows the `Span` that this type is instrumented by.
    pub fn span(&self) -> &Span {
        &self.span
    }

    /// Mutably borrows the `Span` that this type is instrumented by.
    pub fn span_mut(&mut self) -> &mut Span {
        &mut self.span
    }

    /// Borrows the wrapped type.
    pub fn inner(&self) -> &T {
        &self.inner
    }

    /// Mutably borrows the wrapped type.
    pub fn inner_mut(&mut self) -> &mut T {
        &mut self.inner
    }

    /// Get a pinned reference to the wrapped type.
    #[cfg(feature = "std-future")]
    #[cfg_attr(docsrs, doc(cfg(feature = "std-future")))]
    pub fn inner_pin_ref(self: Pin<&Self>) -> Pin<&T> {
        self.project_ref().inner
    }

    /// Get a pinned mutable reference to the wrapped type.
    #[cfg(feature = "std-future")]
    #[cfg_attr(docsrs, doc(cfg(feature = "std-future")))]
    pub fn inner_pin_mut(self: Pin<&mut Self>) -> Pin<&mut T> {
        self.project().inner
    }

    /// Consumes the `Instrumented`, returning the wrapped type.
    ///
    /// Note that this drops the span.
    pub fn into_inner(self) -> T {
        self.inner
    }
}

#[cfg(feature = "std")]
impl<T: Sized> WithSubscriber for T {}

#[cfg(all(feature = "futures-01", feature = "std"))]
#[cfg_attr(docsrs, doc(cfg(all(feature = "futures-01", feature = "std"))))]
impl<T: futures_01::Future> futures_01::Future for WithDispatch<T> {
    type Item = T::Item;
    type Error = T::Error;

    fn poll(&mut self) -> futures_01::Poll<Self::Item, Self::Error> {
        let inner = &mut self.inner;
        dispatcher::with_default(&self.dispatch, || inner.poll())
    }
}

#[cfg(all(feature = "std-future", feature = "std"))]
#[cfg_attr(docsrs, doc(cfg(all(feature = "std-future", feature = "std"))))]
impl<T: crate::stdlib::future::Future> crate::stdlib::future::Future for WithDispatch<T> {
    type Output = T::Output;

    fn poll(self: Pin<&mut Self>, cx: &mut Context<'_>) -> crate::stdlib::task::Poll<Self::Output> {
        let this = self.project();
        let dispatch = this.dispatch;
        let future = this.inner;
        dispatcher::with_default(dispatch, || future.poll(cx))
    }
}

#[cfg(feature = "std")]
impl<T> WithDispatch<T> {
    /// Wrap a future, stream, sink or executor with the same subscriber as this WithDispatch.
    pub fn with_dispatch<U>(&self, inner: U) -> WithDispatch<U> {
        WithDispatch {
            dispatch: self.dispatch.clone(),
            inner,
        }
    }

    /// Borrows the `Dispatch` that this type is instrumented by.
    pub fn dispatch(&self) -> &Dispatch {
        &self.dispatch
    }

    /// Get a pinned reference to the wrapped type.
    #[cfg(feature = "std-future")]
    #[cfg_attr(docsrs, doc(cfg(feature = "std-future")))]
    pub fn inner_pin_ref(self: Pin<&Self>) -> Pin<&T> {
        self.project_ref().inner
    }

    /// Get a pinned mutable reference to the wrapped type.
    #[cfg(feature = "std-future")]
    #[cfg_attr(docsrs, doc(cfg(feature = "std-future")))]
    pub fn inner_pin_mut(self: Pin<&mut Self>) -> Pin<&mut T> {
        self.project().inner
    }

    /// Borrows the wrapped type.
    pub fn inner(&self) -> &T {
        &self.inner
    }

    /// Mutably borrows the wrapped type.
    pub fn inner_mut(&mut self) -> &mut T {
        &mut self.inner
    }

    /// Consumes the `WithDispatch`, returning the wrapped type.
    pub fn into_inner(self) -> T {
        self.inner
    }
}

#[cfg(test)]
pub(crate) use self::support as test_support;
// This has to have the same name as the module in `tracing`.
#[path = "../../tracing/tests/support/mod.rs"]
#[cfg(test)]
#[allow(unreachable_pub)]
pub(crate) mod support;

#[cfg(test)]
mod tests {
    use super::{test_support::*, *};

    #[cfg(feature = "futures-01")]
    mod futures_01_tests {
        use futures_01::{future, stream, task, Async, Future, Stream};
        use tracing::subscriber::with_default;

        use super::*;

        struct PollN<T, E> {
            and_return: Option<Result<T, E>>,
            finish_at: usize,
            polls: usize,
        }

        impl PollN<(), ()> {
            fn new_ok(finish_at: usize) -> Self {
                Self {
                    and_return: Some(Ok(())),
                    finish_at,
                    polls: 0,
                }
            }

            fn new_err(finish_at: usize) -> Self {
                Self {
                    and_return: Some(Err(())),
                    finish_at,
                    polls: 0,
                }
            }
        }

        impl<T, E> futures_01::Future for PollN<T, E> {
            type Item = T;
            type Error = E;
            fn poll(&mut self) -> futures_01::Poll<Self::Item, Self::Error> {
                self.polls += 1;
                if self.polls == self.finish_at {
                    self.and_return
                        .take()
                        .expect("polled after ready")
                        .map(Async::Ready)
                } else {
                    task::current().notify();
                    Ok(Async::NotReady)
                }
            }
        }

        #[test]
        fn future_enter_exit_is_reasonable() {
            let (subscriber, handle) = subscriber::mock()
                .enter(span::mock().named("foo"))
                .exit(span::mock().named("foo"))
                .enter(span::mock().named("foo"))
                .exit(span::mock().named("foo"))
                .drop_span(span::mock().named("foo"))
                .done()
                .run_with_handle();
            with_default(subscriber, || {
                PollN::new_ok(2)
                    .instrument(tracing::trace_span!("foo"))
                    .wait()
                    .unwrap();
            });
            handle.assert_finished();
        }

        #[test]
        fn future_error_ends_span() {
            let (subscriber, handle) = subscriber::mock()
                .enter(span::mock().named("foo"))
                .exit(span::mock().named("foo"))
                .enter(span::mock().named("foo"))
                .exit(span::mock().named("foo"))
                .drop_span(span::mock().named("foo"))
                .done()
                .run_with_handle();
            with_default(subscriber, || {
                PollN::new_err(2)
                    .instrument(tracing::trace_span!("foo"))
                    .wait()
                    .unwrap_err();
            });

            handle.assert_finished();
        }

        #[test]
        fn stream_enter_exit_is_reasonable() {
            let (subscriber, handle) = subscriber::mock()
                .enter(span::mock().named("foo"))
                .exit(span::mock().named("foo"))
                .enter(span::mock().named("foo"))
                .exit(span::mock().named("foo"))
                .enter(span::mock().named("foo"))
                .exit(span::mock().named("foo"))
                .enter(span::mock().named("foo"))
                .exit(span::mock().named("foo"))
                .drop_span(span::mock().named("foo"))
                .run_with_handle();
            with_default(subscriber, || {
                stream::iter_ok::<_, ()>(&[1, 2, 3])
                    .instrument(tracing::trace_span!("foo"))
                    .for_each(|_| future::ok(()))
                    .wait()
                    .unwrap();
            });
            handle.assert_finished();
        }

        #[test]
        fn span_follows_future_onto_threadpool() {
            let (subscriber, handle) = subscriber::mock()
                .enter(span::mock().named("a"))
                .enter(span::mock().named("b"))
                .exit(span::mock().named("b"))
                .enter(span::mock().named("b"))
                .exit(span::mock().named("b"))
                .drop_span(span::mock().named("b"))
                .exit(span::mock().named("a"))
                .drop_span(span::mock().named("a"))
                .done()
                .run_with_handle();
            let mut runtime = tokio::runtime::Runtime::new().unwrap();
            with_default(subscriber, || {
                tracing::trace_span!("a").in_scope(|| {
                    let future = PollN::new_ok(2)
                        .instrument(tracing::trace_span!("b"))
                        .map(|_| {
                            tracing::trace_span!("c").in_scope(|| {
                                // "c" happens _outside_ of the instrumented future's
                                // span, so we don't expect it.
                            })
                        });
                    runtime.block_on(Box::new(future)).unwrap();
                })
            });
            handle.assert_finished();
        }
    }

    #[cfg(all(feature = "futures-03", feature = "std-future"))]
    mod futures_03_tests {
        use futures::{future, sink, stream, FutureExt, SinkExt, StreamExt};
        use tracing::subscriber::with_default;

        use super::*;

        #[test]
        fn stream_enter_exit_is_reasonable() {
            let (subscriber, handle) = subscriber::mock()
                .enter(span::mock().named("foo"))
                .exit(span::mock().named("foo"))
                .enter(span::mock().named("foo"))
                .exit(span::mock().named("foo"))
                .enter(span::mock().named("foo"))
                .exit(span::mock().named("foo"))
                .enter(span::mock().named("foo"))
                .exit(span::mock().named("foo"))
                .drop_span(span::mock().named("foo"))
                .run_with_handle();
            with_default(subscriber, || {
                stream::iter(&[1, 2, 3])
                    .instrument(tracing::trace_span!("foo"))
                    .for_each(|_| future::ready(()))
                    .now_or_never()
                    .unwrap();
            });
            handle.assert_finished();
        }

        #[test]
        fn sink_enter_exit_is_reasonable() {
            let (subscriber, handle) = subscriber::mock()
                .enter(span::mock().named("foo"))
                .exit(span::mock().named("foo"))
                .enter(span::mock().named("foo"))
                .exit(span::mock().named("foo"))
                .enter(span::mock().named("foo"))
                .exit(span::mock().named("foo"))
                .drop_span(span::mock().named("foo"))
                .run_with_handle();
            with_default(subscriber, || {
                sink::drain()
                    .instrument(tracing::trace_span!("foo"))
                    .send(1u8)
                    .now_or_never()
                    .unwrap()
                    .unwrap()
            });
            handle.assert_finished();
        }
    }
}