Added Vec append to BufferVec - Issue #3531

[Connor-McMillin]

Objective

• Fixes Expose more of the Vec API on BufferVec #3531

Solution

• Added an append wrapper to BufferVec based on the function signature for vec.append()

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First PR to Bevy. I didn't see any tests for other BufferVec methods (could have missed them) and currently this method is not used anywhere in the project. Let me know if there are tests to add or if I should find somewhere to use append so it is not dead code. The issue mentions implementing truncate and extend which were already implemented and merged here

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[alice-i-cecile]

I would like to see a couple of simple tests for this: seems like useful functionality both internally and externally but I agree that dead code is rough.

[Connor-McMillin]

Are there any other vector functions that should get added with this PR?

[Connor-McMillin]

Thanks @mockersf for pointing out that I needed to make the function public. This also resolved the dead code warnings, although I don't know why it doesn't detect this as dead code anymore.

The tests I wrote (and momentarily pushed to this branch)

• Didn't resolve the dead code warning
• Could not easily use a test struct that derives Pod because that requires a dependency on bytemuck which bevy_render doesn't require currently and requiring that dependency for one or two tests doesn't seem like a good idea
• Were pretty gross using Mat4 and matrix operations in assertions. This was one of the objects I found that derives Pod and didn't require additional dependencies to other projects

So I think just the implementation sans tests probably makes the most sense and is in line with the rest of BufferVec not being tested directly

[mockersf]

Thanks @mockersf for pointing out that I needed to make the function public. This also resolved the dead code warnings, although I don't know why it doesn't detect this as dead code anymore.

Because it's now part of the exposed public API, so it can be used by caller of the lib