Allow zero-valued LP Python model updates

[fallintoplace]

Summary

Problem.updateConstraint and Problem.updateObjective used truthiness checks for optional numeric updates. That meant valid zero values such as rhs=0 or constant=0 were silently ignored.

This updates those checks to distinguish omitted arguments from explicit zero-valued updates. It also removes the mutable default list from both methods while keeping the existing call behavior.

Validation

• python3 -m py_compile python/cuopt/cuopt/linear_programming/problem.py python/cuopt/cuopt/tests/linear_programming/test_python_API.py
• git diff --check

Not run locally: PYTHONPATH=python/cuopt uvx --with 'pytest<9.0' pytest python/cuopt/cuopt/tests/linear_programming/test_python_API.py -k 'problem_update_accepts_zero_values' -q could not collect because this checkout does not include the generated/native cuopt.linear_programming.internals.internals module.

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📥 Commits

Reviewing files that changed from the base of the PR and between c99a5ce and c552401.

📒 Files selected for processing (2)

• python/cuopt/cuopt/linear_programming/problem.py
• python/cuopt/cuopt/tests/linear_programming/test_python_API.py

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📝 Walkthrough

Walkthrough

The PR fixes mutable default arguments and improves parameter handling in two Problem class methods. updateConstraint and updateObjective now use None defaults instead of empty lists, and both methods respect falsy numeric values like 0 instead of skipping them during updates.

Changes

Mutable defaults and falsy value handling

Layer / File(s)	Summary
updateConstraint method fix python/cuopt/cuopt/linear_programming/problem.py	Method signature changes coeffs parameter default from mutable [] to None. Implementation initializes coeffs to an empty list when omitted and updates constr.RHS only when rhs is not None, allowing zero to be a valid RHS value.
updateObjective method fix python/cuopt/cuopt/linear_programming/problem.py	Method signature changes coeffs parameter default from mutable [] to None. Implementation normalizes coeffs to an empty list when omitted, updates ObjConstant only when constant is not None, and updates ObjSense only when sense is not None, ensuring zero and falsy enum values are correctly applied.
Test coverage for zero values python/cuopt/cuopt/tests/linear_programming/test_python_API.py	New test test_problem_update_accepts_zero_values validates that constraint RHS and objective constant can be set to zero without being ignored.

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Estimated code review effort

🎯 2 (Simple) | ⏱️ ~12 minutes

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Suggested labels

non-breaking, improvement

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Suggested reviewers

• rgsl888prabhu
• tmckayus

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 62.50% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title 'Allow zero-valued LP Python model updates' directly and clearly summarizes the main change: enabling explicit zero values in LP model update methods.
Description check	✅ Passed	The description is directly related to the changeset, explaining the problem (truthiness checks ignoring zero values), the solution (distinguishing omitted arguments from explicit zeros, removing mutable defaults), and validation steps performed.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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