Add RL unit tests: normalize and match_approximately

[hengtaoguo]

Description

Add two unit tests for RL utils:

• normalize_final_answer: Various numeric/string formats ("1,000", "$100", "\boxed{100}", etc.)
• match_format_approximately: Test reward/penalty logic with 0-4 matching tokens

Tests

CI

Checklist

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• I have made or will make corresponding changes to the doc if needed, including adding new documentation pages to the relevant Table of Contents (toctree directive) as explained in our documentation.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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[github-actions]

🤖 Hi @hengtaoguo, I've received your request, and I'm working on it now! You can track my progress in the logs for more details.

[github-actions]

## 📋 Review Summary

This PR successfully adds comprehensive unit tests for normalize_final_answer and match_format_approximately in the RL utilities. The added tests correctly evaluate formatting rewards and penalties as well as string normalization edge cases, contributing to better test coverage for RL post-training functionality.

🔍 General Feedback

• Positive Highlight: The test coverage for normalize_final_answer correctly anticipates and verifies several tricky LaTeX edge cases such as wrapper extraction and shorthand expansions.
• Testing Pattern: Consider breaking down monolithic test methods with multiple assertions (as seen in test_partial_format_scores and test_normalize_final_answer) into smaller, isolated test cases to improve diagnosability.
• The mixing of unittest.TestCase with @pytest.mark.cpu_only remains consistent with the rest of the testing suite in this file, so no immediate action is needed on that front.

[richjames0]

lgtm