(WIP): Adding Stream mock to tokio-test #4463

Grubba27 · 2022-02-02T21:54:24Z

Motivation

This issue relates to #4106

Solution

Test the Stream with the mock as sugested in issue thread

This is a draft. I got stuck creating the solution, created this PR in hope that I could get some help

Darksonn

Let me know if there's any other help you need.

Darksonn · 2022-02-06T15:22:42Z

tokio-test/src/io.rs

+#[derive(Debug, Clone, Default)]
+pub struct StreamBuilder {
+    // Sequence of actions for the Mock to take
+    actions: VecDeque<Action>,
+}


I think this should go in its own file.

Darksonn · 2022-02-06T15:24:00Z

tokio-test/src/io.rs

+    /// call next value ?
+    pub fn poll_next(&mut self, buf: &[u8]) {
+        /// TODO
+    }


You should not be able to call poll_next or next on the builder. You have to actually build it first. The io builder also doesn't implement AsyncRead or AsyncWrite.

Grubba27 · 2022-02-08T01:42:44Z

Let me know if there's any other help you need.

Sure! I'm trying to get to know Tokio code base and its patterns.
Should I create also a file just for io_stream ? also I'm not sure how I would implement stream in Mock and how I would test it if not by let val = stream.next().await as stream here would be building mock as stream ? like in the return of mock -> impl Stream<value = &str>

Darksonn · 2022-02-08T07:01:41Z

tokio-test/src/io_stream.rs

+    fn read(&mut self, dst: &mut ReadBuf<'_>) -> io::Result<()> {
+        match self.action() {
+            Some(&mut Action::Read(ref mut data)) => {


You are implementing a Stream. Streams do not have a read or write method. Instead, you should make an impl Stream for Mock block so that Mock becomes a stream.

now I see where I need to go. In impl Steam for Mock i should use :

type Item = String; // like this because my mock would only use Strings as their items ?

then i would do something like pop from an array or like a loop from async read or async write within poll_next ? like this:

fn poll_next(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Option<Self::Item>> { // TODO // Pop item from array who could i iterate self? or do a while loop like in AsyncRead /AsyncWrite ? Poll::Pending }

Darksonn · 2022-02-08T07:03:36Z

tokio-test/src/io_stream.rs

+#[derive(Debug, Clone, Default)]
+pub struct Builder {
+    // Sequence of actions for the Mock to take
+    actions: VecDeque<Action>,
+}
+#[derive(Debug, Clone, Default)]
+pub struct StreamBuilder {
+    // Sequence of actions for the Mock to take
+    actions: VecDeque<Action>,
+}


Why are there two builders?

Sorry :/ I was sleppy but I did remove these two now

Darksonn · 2022-02-08T07:05:02Z

also I'm not sure how I would implement stream in Mock and how I would test it if not by let val = stream.next().await as stream here would be building mock as stream

You would test it by calling next on the Mock value as you suggested.

Darksonn · 2022-02-09T09:09:45Z

tokio-test/src/io_stream.rs

+impl Stream for Mock {
+    type Item = String;
+
+    fn poll_next(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
+        // TODO
+        // Pop item from array who could i iterate self? or do a  while loop like in AsyncRead /AsyncWrite ?
+        Poll::Pending
+    }
+
+}


Basically you need to return the next action from the list of actions, but if that action is a sleep, then you need to sleep instead. And if you are polled during a sleep, you need to keep sleeping until the sleep completes.

The other mock type implements this by having a loop, where the loop first checks if its currently sleeping, then if the ready! macro lets it get past the sleep (i.e. if the sleep has completed), then it pops the next item. If the next item is a sleep, then it sets up that new sleep and goes around the loop. Otherwise it returns the item.

Darksonn · 2022-02-10T09:59:44Z

tokio-test/src/io_stream.rs

+            match ready!(self.inner.poll_action(_cx))  {
+                None => {
+                    return Poll::Pending;


If poll_action returns None, then isn't that because we are at the end and the stream is complete? Then you should return Poll::Ready(None) instead of Poll::Pending.

Okay now I see what I was doing wrong!!
I don't have any ideia why my mock.next.await is aways returning None for me. perhaps because of the cx ?
Maybe I should use a mock Context too for using pool_next(cx) ? or keep with next() but change the way that I call Action it at io_steram ?

Darksonn · 2022-06-30T09:53:58Z

Sorry, this PR appears to have gotten lost. Do you want to finish it? There are some CI failures.

Grubba27 · 2022-06-30T14:33:52Z

Sorry, this PR appears to have gotten lost. Do you want to finish it? There are some CI failures.

Yeah, I Would love to finish. It has been some time since I haven't touched Rust but I can give it another try again guess this last note can help me :

I don't have any ideia why my mock.next.await is aways returning None for me. perhaps because of the cx ? Maybe I should use a mock Context too for using pool_next(cx) ? or keep with next() but change the way that I call Action it at io_steram ?

Darksonn · 2022-06-30T14:37:43Z

tokio-test/src/io_stream.rs

+impl Stream for Mock {
+    type Item = String;
+
+    fn poll_next(mut self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
+
+        loop {
+            if let Some(ref mut sleep) = self.inner.sleep {
+                ready!(Pin::new(sleep).poll(_cx));
+            }
+
+
+            // If a sleep is set, it has already fired
+            self.inner.sleep = None;
+            match ready!(self.inner.poll_action(_cx))  {
+                Some(action) => {
+                    self.inner.actions.push_back(action);
+                    continue;
+                }
+                None => {
+                    return Poll::Ready(None);
+                }
+            }
+        }
+
+    }


The poll_next function never returns Poll::Ready(Some(...)) anywhere, so the stream never produces any items.

OMG!! I think I got it(copilot also helped me understand)
Guess the only thing that is missing is

let now = Instant::now(); if now < until { break; } } else { self.waiting = Some(Instant::now() + *dur); break; }

for this method:

self.inner.sleep = Some(delay_for(dur)); }

copilot could not help in those.

The fact that you're trying to use delay_for shows that you're looking at old documentation. It was renamed to sleep in Tokio 1.x.y.

Please check out the documentation for Sleep. You need to use the reset method to update the deadline. There are examples in the docs.

tokio-test/src/io_stream.rs

Co-authored-by: devensiv <devensiv@gmail.com>

Darksonn · 2023-04-16T14:48:58Z

Hey, I'm really sorry that this got lost. Do you still want to work on it? If not, that's ok.

Darksonn · 2023-11-25T12:10:14Z

This has been superseded by #5915.

(WIP): Draft of PR

63e5fb3

Grubba27 changed the title ~~(WIP): Draft of PR~~ (WIP): Add Stream mock to tokio-test Feb 2, 2022

Grubba27 changed the title ~~(WIP): Add Stream mock to tokio-test~~ (WIP): Adding Stream mock to tokio-test Feb 2, 2022

Added stream builder

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Darksonn added the A-tokio-test Area: The tokio-test crate label Feb 6, 2022

Darksonn reviewed Feb 6, 2022

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Grubba27 added 2 commits February 7, 2022 22:33

started adjusting and addressing comments

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adjusted rust rust lint

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run cargo clippy

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Darksonn reviewed Feb 8, 2022

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Grubba27 added 5 commits February 8, 2022 19:55

started addressing comments

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adjusted comments

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removed ./idea files

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removed ./idea files

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removed StreamBuilder struct from io

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Darksonn reviewed Feb 9, 2022

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Grubba27 added 3 commits February 9, 2022 19:57

addresed comments

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ran rust linter

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adjusted stream read and next

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Darksonn reviewed Feb 10, 2022

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started addressing comments

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Merge branch 'tokio-rs:master' into issue-4106

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Darksonn reviewed Jun 30, 2022

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Grubba27 added 2 commits June 30, 2022 11:54

fix: adjusted missing returns

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fix compilation errors

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devensiv reviewed Mar 19, 2023

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tokio-test/src/io_stream.rs Outdated Show resolved Hide resolved

Update tokio-test/src/io_stream.rs

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Co-authored-by: devensiv <devensiv@gmail.com>

Darksonn closed this Nov 25, 2023

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(WIP): Adding Stream mock to tokio-test #4463

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(WIP): Adding Stream mock to tokio-test #4463

(WIP): Adding Stream mock to tokio-test #4463

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Grubba27 commented Feb 2, 2022

Motivation

Solution

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