Custom assert_eq! or Vec Eq

help
1

For testing purposes, I have two Vecs of references.

If I try to compare them via assert_eq!, it fails:

assert_eq!(clips, vec![clip_0, clip_1]);
//error[E0369]: binary operation `==` cannot be applied to type `std::vec::Vec<&components::tweens::Tween>`

However, I can compare their elements with std::ptr::eq:

assert!(std::ptr::eq(clips[0], clip_0));
assert!(std::ptr::eq(clips[1], clip_1));

Is there some way to tell assert_eq! (or these Vec's Eq...) to use std::ptr::eq?

Alternatively, if I'm barking up the wrong tree in terms of that solution - a better approach is appreciated :slight_smile:

2

std::ptr::eq only compares pointers (i.e. memory addresses), not values, so that's probably not what you want here.

Fundamentally, components::tweens::Tween needs an Eq implementation, or you simply can't compare Tween values. It may be possible to work around this in your code with a wrapper type if Tween publicly exposes all the data relevant to a comparison, but even that would require constant wrapping and unwrapping.

If you really do want to compare memory addresses, then AFAIK there are no dedicated assert macros for that and assert!(std::ptr::eq(...)); is the way to go. Even references intentionally do value comparisons because that's overwhelmingly more common, so when you really want addresses you just have to go outside the Eq trait entirely.

3

Yeah - this use-case is specifically for running tests where I want to make sure the references match, e.g. that operations like "give me all the tweens at this point in time" are exactly the ones I expect.

Thanks, will stick with the verbose solution for now :slight_smile:

4

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