Injecting static types

[antimora]

I have a burn-tensor crate that defines tensor operations and traits, and I have separate backend crates (burn-ndarray and burn-tch) that implement these traits for specific tensor backends.

How can I use rstest to write tests for the tensor operations in the burn-tensor crate and inject static backend types into the tests?

A couple of constraints that I wish to keep: 1) I do not want to define macro in burn-tensor crate that will be re-imported into the backend crates (this is how it's currently done 2) I do not want burn-tensor to depend on the backend crates.

[la10736]

Sorry, but I'm not sure to have understood your question. Do you want to write some tests and apply them on the 2 backends?

Something like the follow code?

trait MyTrait {
    fn get() -> u32;
}

struct A;
struct B;

impl MyTrait for A {
    fn get() -> u32 {
        42
    }
}

impl MyTrait for B {
    fn get() -> u32 {
        84
    }
}

use rstest::rstest;
use std::marker::PhantomData;

#[rstest]
#[case(PhantomData::<A>)]
#[case(PhantomData::<B>)]
fn test_get<T: MyTrait>(#[case] _a: PhantomData<T>) {
    assert_eq!(T::get() % 2, 0);
}

You can also use rstest_reuse to spread these cases to some tests.

[antimora]

@a10736, thank you so much for you suggestion and great examples. rstest_reuse is a great pointer. I didn't know about it.

Continuing with your example, let me clarify.

Basically, I need to have MyTrait and the unit tests defined in crate "MyTraitAndTests". And the trait implementations in "ImplA" and "ImplB" crates, which will consume the unit tests defined in "MyTraitAndTests". It would very convenient when I import the unit tests, I can pass type A (that implements MyTrait) to a whole suit without referencing individual methods. It seems rstest_reuse supports such use case, correct?