burn-import: add some tests for ConstantNode

[jameshiew]

Pull Request Template

Checklist

• Confirmed that run-checks all script has been executed.
• Made sure the book is up to date with changes in this PR.

Related Issues/PRs

I've been trying to implement OneHot ONNX op (#1714) in a WIP draft branch. The ONNX model ends up containing a constant integer vector values=[0, 1] used by the OneHot op, this vector was causing issues when trying to test the model. I looked at ConstantNode and these are the tests so far I could get working while investigating.

Issues for ConstantNode
#2624 - constant tensors aren't populated with values
#2625 - generated code for const int tensors doesn't compile

Changes

• added a helper method ConstantNode::tensor_ty_tokens for tests, but this PR otherwise shouldn't be changing how ConstantNode currently works
• add codegen tests for ConstantNode (i32/64 + f32/64 scalar, tensors)
• add ONNX model tests for i32/64 + f32/64 scalars - implicitly testing by adding the constant

Testing

Ran added tests

cargo xtask check all
cargo nextest run --manifest-path crates/burn-import/Cargo.toml
cargo nextest run --manifest-path crates/burn-import/onnx-tests/Cargo.toml

I checked the .onnx models contain the expected scalar constants using Netron

Screenshots

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 80.91%. Comparing base (5d16339) to head (83458c6).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2623      +/-   ##
==========================================
+ Coverage   80.84%   80.91%   +0.06%     
==========================================
  Files         872      872              
  Lines      120725   121039     +314     
==========================================
+ Hits        97605    97938     +333     
+ Misses      23120    23101      -19     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[github-actions]

This PR has been marked as stale because it has not been updated for over a month

[laggui]

Was going through pending PRs, figured I'd apply the suggested changes myself 😅 so we can finally close this