`WaitForTopics`: let the user inject a callaback to be executed after starting the subscribers #356

LastStarDust · 2023-03-01T05:58:52Z

I created this pull request as a proof of concept for the new feature discussed here: #348.
The ticket description is still correct and relevant, but for clarity's sake, let me summarize and expand on it here.

Let us assume there is a node ("NODE under test" in the diagram) which:

takes a topic A as input
does some calculation
publishes another topic B as output

At the moment, there is no way to programmatically test the whole node end-to-end. For that, we need a way to:

inject a message of topic A into the node
wait for the calculation to be over
collect the resulting message of topic B coming out of the node

Currently, the WaitForTopics class provided by this package takes care of 2 and 3, but there is no mechanism to reliably accomplish 1, due to the asynchronous nature of ROS2 publishers and subscribers.

This PR is an attempt to enhance the WaitForTopics class so that it can take care of 1 as well, thus closing the loop. But it might well not be the only solution or the most effective. I am open to any kind of suggestion and guidance.

The main issue behind the implementation of such a feature is that in ROS2 the order of creation of publishers and subscribers does matter. They must either always be created in a specific order or be synchronized in some other way.

Below is a cartoon-style diagram illustrating what the end result should look like:

adityapande-1995

I've posted some questions worth discussing here : #348 (comment)

LastStarDust · 2023-03-13T07:24:12Z

I've posted some questions worth discussing here : #348 (comment)

@adityapande-1995 @clalancette I have added a more comprehensive sample code in commit 5aa51d7

LastStarDust · 2023-05-22T03:42:25Z

@adityapande-1995 @clalancette
Hello and sorry for the comment. Is there anything I can do to help with the review of this pull request?

LastStarDust · 2023-05-29T13:32:08Z

@osrf-jenkins retest this please

LastStarDust · 2023-06-26T06:06:51Z

@adityapande-1995 @clalancette
Let me present a thought experiment that might make clearer what I am trying to achieve with this pull request.

How would you test a node that is subscribed to a topic with a single int field, that publishes the same topic where the int was incremented by one?

LastStarDust · 2023-06-26T06:07:30Z

@osrf-jenkins retest this please

LastStarDust · 2023-09-16T03:37:50Z

@adityapande-1995 @methylDragon
Friendly reminder about this PR.

Until now, I have been using my fork at work for our project, but it would give us more confidence if we could just use the official repository, or even better if this PR could end up in the released version on https://index.ros.org/packages/.

LastStarDust · 2023-09-16T03:41:03Z

@osrf-jenkins retest this please

adityapande-1995 · 2023-09-28T17:07:08Z

@LastStarDust my apologies, taking a look now

launch_testing_ros/test/examples/wait_for_topic_inject_callback.py

LastStarDust · 2024-02-01T06:05:54Z

@adityapande-1995 @methylDragon I fixed some linting errors and now the checks are finally passing.

Ryanf55 · 2024-02-15T19:38:24Z

Hello, could we get a maintainer to look at this PR?

mjcarroll · 2024-02-20T14:52:16Z

@methylDragon is OOO, but I will ping him to look when he is back.

Ryanf55

I tested this on a backport in humble in our own CI and it is very reliable with some minor mods.

launch_testing_ros/launch_testing_ros/wait_for_topics.py

launch_testing_ros/test/examples/repeater.py

launch_testing_ros/test/examples/wait_for_topic_inject_callback.py

launch_testing_ros/launch_testing_ros/wait_for_topics.py

LastStarDust · 2024-07-03T07:59:03Z

@Ryanf55 Hello, I would like to resume working on this PR. Could you please take a look at the conversations you opened and resolve the ones you think are resolved?

LastStarDust · 2024-07-03T08:00:49Z

@osrf-jenkins retest this please

Ryanf55 · 2024-07-09T16:58:13Z

@Ryanf55 Hello, I would like to resume working on this PR. Could you please take a look at the conversations you opened and resolve the ones you think are resolved?

Yep, all of the issues we found are still problems, and we never found a good workaround for doing this generically in humble. For now, we disabled our python automated testing as a requirement for PR's because this problem is so difficult to deal with, and have focused testing without the middleware. Once we can move to Jazzy, then the event handlers should make this kind of testing much more reliable because you can do a proper wait on the interfaces to come up.

Sorry, we've just spent an exorbitant amount of time on this trying to get this reliable in humble and could never figure out a way that wasn't extremely coupled to knowing exactly what was running and manual graph introspection hard-coded into our test framework. I'm optimistic that upgrading distros will make it easier, but this way of testing in python is not something we're going to pursue any further unless anyone can give us a reasonable approach that works without hard-coded timeouts/sleeps for discovery that fail on slower runners.

LastStarDust · 2024-07-09T23:06:06Z

@Ryanf55 Thank you for sharing the situation. I am sorry we could not figure out how to make this work reliably in Humble.
Anyway, can I resolve the discussions opened by you in this PR, since it applies to rolling?

Signed-off-by: Giorgio Pintaudi <[email protected]> Updates the `WaitForTopics` class to use the term 'trigger' instead of 'callback' for the function executed during the wait. This change clarifies the function's purpose, which is to trigger an action rather than simply provide a callback.

Signed-off-by: Giorgio Pintaudi <[email protected]> Passes the timeout value to the `any_publisher_connected.wait()` call. This ensures that the wait for any publisher connection respects the specified timeout, preventing indefinite blocking.

Signed-off-by: Giorgio Pintaudi <[email protected]> Allows specifying a namespace for the internal node created by `WaitForTopics`. This enables better organization and avoids potential naming conflicts when using `wait_for_topics` in complex launch setups.

Signed-off-by: Giorgio Pintaudi <[email protected]> Co-authored-by: Christophe Bedard <[email protected]> Signed-off-by: Giorgio Pintaudi <[email protected]>

…t_trigger_test.py Signed-off-by: Giorgio Pintaudi <[email protected]>

Signed-off-by: Giorgio Pintaudi <[email protected]> Adds a blank line after the disable-windows-cli-blocking pragma for improved code style and readability.

mergify · 2025-04-15T00:54:46Z

rebase

✅ Branch has been successfully rebased

LastStarDust · 2025-04-15T01:14:25Z

@christophebedard I think the DCO check is failing after your rebase. I am not sure how to fix that. My guess is that you need to add your sign to each commit.

christophebedard · 2025-04-15T01:39:16Z

It's OK, I can just manually set it to pass.

christophebedard · 2025-04-15T02:01:19Z

Pulls: #356
Gist: https://gist.githubusercontent.com/christophebedard/ce2a429b7640973274d34dc3ad9a9838/raw/6af87c7d846ad03e8f86b90fe1e969c071163a64/ros2.repos
BUILD args: --packages-above-and-dependencies launch_testing_ros
TEST args: --packages-above launch_testing_ros
ROS Distro: rolling
Job: ci_launcher
ci_launcher ran: https://ci.ros2.org/job/ci_launcher/15697

Linux
Linux-aarch64
Linux-rhel
Windows

christophebedard

Alright, I think this PR is in a good state and I think the approach helps reduce flakiness.

Let's see if CI passes.

christophebedard · 2025-04-15T05:08:25Z

The ros2param test failures are known.

christophebedard · 2025-04-15T05:18:09Z

@LastStarDust it might be worth updating/expanding the integration testing tutorial added in ros2/ros2_documentation#4881 to show an example of WaitForTopics (ros2/ros2_documentation#4881 (comment)) instead of simply mentioning it. Let me know if you'd be willing to do that, otherwise I will open an issue!

christophebedard · 2025-04-19T16:51:31Z

I created an issue for it: ros2/ros2_documentation#5249

LastStarDust · 2025-04-24T13:47:21Z

@christophebedard Yes, I am available to improve the documentation. I hope more people become interested in integration testing of ROS2 nodes, and as a result, we will see more advanced and flexible tooling developed.

christophebedard · 2025-06-21T22:16:38Z

@LastStarDust do you still want this PR to be backported to Jazzy? I got an email notification, but I can't find your comment anymore

LastStarDust · 2025-06-22T21:05:40Z

@christophebedard
I deleted that comment because I found a (small) bug in this PR in the meanwhile. I am going to open a new PR with the bugfix (#474)

Once all the bugs are ironed out and I am 100% sure this is working as intended, then we can port this to Jazzy.

ahcorde · 2025-11-19T11:07:01Z

https://github.com/Mergifyio backport kilted jazzy

mergify · 2025-11-19T11:07:20Z

backport kilted jazzy

✅ Backports have been created

Backport to branch kilted not needed, change already in branch kilted
#504 WaitForTopics: let the user inject a callaback to be executed after starting the subscribers (backport #356) has been created for branch jazzy

…d after starting the subscribers (#356) Signed-off-by: Giorgio Pintaudi <[email protected]> (cherry picked from commit 1e33f0a)

… starting the subscribers (backport #356) (#504) * `WaitForTopics`: let the user inject a trigger function to be executed after starting the subscribers (#356) Signed-off-by: Giorgio Pintaudi <[email protected]> (cherry picked from commit 1e33f0a)

LastStarDust requested review from adityapande-1995 and methylDragon as code owners March 1, 2023 05:58

LastStarDust changed the title ~~Let the user inject callables after starting subscribers~~ WaitForTopics: let the user inject callables after starting subscribers Mar 1, 2023

adityapande-1995 mentioned this pull request Mar 1, 2023

WaitForTopics: there is no way to manually trigger a topic #348

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adityapande-1995 reviewed Mar 1, 2023

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LastStarDust mentioned this pull request Mar 10, 2023

WaitForTopics: get content of messages for each topic #353

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LastStarDust force-pushed the feature/inject-callables branch from 3f96cb5 to b8004ab Compare May 22, 2023 04:30

Ryanf55 mentioned this pull request Aug 16, 2023

Add async support for subscribing messages #375

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methylDragon reviewed Oct 13, 2023

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launch_testing_ros/test/examples/wait_for_topic_inject_callback.py Outdated Show resolved Hide resolved

LastStarDust changed the title ~~WaitForTopics: let the user inject callables after starting subscribers~~ WaitForTopics: let the user inject callables to be executed after starting the subscribers Feb 1, 2024

LastStarDust changed the title ~~WaitForTopics: let the user inject callables to be executed after starting the subscribers~~ WaitForTopics: let the user inject callabacks to be executed after starting the subscribers Feb 16, 2024

LastStarDust changed the title ~~WaitForTopics: let the user inject callabacks to be executed after starting the subscribers~~ WaitForTopics: let the user inject a callaback to be executed after starting the subscribers Feb 16, 2024

Ryanf55 suggested changes Feb 20, 2024

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launch_testing_ros/launch_testing_ros/wait_for_topics.py Show resolved Hide resolved

launch_testing_ros/test/examples/repeater.py Show resolved Hide resolved

launch_testing_ros/test/examples/wait_for_topic_inject_callback.py Show resolved Hide resolved

Ryanf55 reviewed Feb 21, 2024

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Ryanf55 mentioned this pull request Feb 21, 2024

Increase the timeout in wait_for_topic_launch_test. #377

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LastStarDust and others added 7 commits April 15, 2025 00:54

Passes timeout to publisher connection wait

3a208bc

Signed-off-by: Giorgio Pintaudi <[email protected]> Passes the timeout value to the `any_publisher_connected.wait()` call. This ensures that the wait for any publisher connection respects the specified timeout, preventing indefinite blocking.

Apply suggestions from code review

c7e9f72

Signed-off-by: Giorgio Pintaudi <[email protected]> Co-authored-by: Christophe Bedard <[email protected]> Signed-off-by: Giorgio Pintaudi <[email protected]>

Apply suggestions from code review

6d53d29

Signed-off-by: Giorgio Pintaudi <[email protected]> Co-authored-by: Christophe Bedard <[email protected]> Signed-off-by: Giorgio Pintaudi <[email protected]>

Rename wait_for_topic_inject_callback_test.py to wait_for_topic_injec…

aa6fc44

…t_trigger_test.py Signed-off-by: Giorgio Pintaudi <[email protected]>

Adds a blank line for code style consistency

3c52fdd

Signed-off-by: Giorgio Pintaudi <[email protected]> Adds a blank line after the disable-windows-cli-blocking pragma for improved code style and readability.

christophebedard force-pushed the feature/inject-callables branch from d8866da to 3c52fdd Compare April 15, 2025 00:54

christophebedard approved these changes Apr 15, 2025

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christophebedard merged commit 1e33f0a into ros2:rolling Apr 15, 2025
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christophebedard mentioned this pull request Apr 19, 2025

Add WaitForTopics example to integration testing tutorial ros2/ros2_documentation#5249

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LastStarDust deleted the feature/inject-callables branch May 12, 2025 09:25

LastStarDust mentioned this pull request Jun 22, 2025

WaitForTopics: wait for publisher-subscriber connection to be established #474

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mergify bot pushed a commit that referenced this pull request Nov 19, 2025

WaitForTopics: let the user inject a trigger function to be execute…

9510bba

…d after starting the subscribers (#356) Signed-off-by: Giorgio Pintaudi <[email protected]> (cherry picked from commit 1e33f0a)

WaitForTopics: let the user inject a callaback to be executed after starting the subscribers #356

WaitForTopics: let the user inject a callaback to be executed after starting the subscribers #356

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`WaitForTopics`: let the user inject a callaback to be executed after starting the subscribers #356

`WaitForTopics`: let the user inject a callaback to be executed after starting the subscribers #356

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