Executing tests on a spawned thread

[niclo]

In the book it states tests can be executed asynchronously as such:

#[tokio::main]
async fn main() {
    AnimalWorld::run("tests/features/book/quickstart").await;
}

However in my use case, that being a web server which receives a request to execute a cucumber test, I would like to run said test on a separate thread, allowing the handler to exit and once the test has been executed, the result is saved to a database. Naively I went with something like this:

tokio::spawn(async {
    AnimalWorld::cucumber().fail_fast().run("tests/features/book/quickstart").await;
});

However this does not work because future is not Send. I looked into a potential solution from tokio for this problem, however I do not think it would work with what I am trying to do.

Therefore I was wondering if the cucumber-rs team might have already encountered this particular use case and could kindly point me in the right direction. Thank you :)

[ilslv]

@niclo I'm not quite sure I understand the use-case here.

I would like to run said test on a separate thread

tokio::spawn doesn't guarantee that Future will be executed on a separate thread

allowing the handler to exit and once the test has been executed, the result is saved to a database.

Can you elaborate?

[niclo]

Thank you for your fast response!

The http server has access to a registry of devices. Currently a user can send a request to manipulate certain characteristics of a device, for instance, updating the firmware of a given device. I would like to expand upon the server, by allowing users to send a request to run a specific test against a given device. That is why I need to call, e.g., AnimalWorld::run() outside of main(). The result of the test is then saved to the database, so that the user can send another request to see whether or not the test was successful.

Another solution I am currently looking into is using std::process::Command to execute the test on a separate process instead of a separate thread.

Essentially I would just like to know if some form of this

tokio::spawn(async {
    AnimalWorld::run("tests/features/book/quickstart").await;
});

is possible or not. Thank you very much :)

[ilslv]

@niclo in case your tests do not contain significant blocking logic, there is no need to run tests in a separate thread. Just use .await. In case there is blocking code, you should wrap it in a tokio::spawn_blocking.

Alternatively you can spawn a thread, spin up a new tokio runtime and then block on World::run().

[niclo]

Alright thank you 🙏🏼