test: Add integration tests for CrossValidators module [P1]

[ooples]

Overview

This issue tracks integration tests for the CrossValidators module. P1 (High Priority).

Parent Issue: #615

Current Status

• Coverage: 0%
• Source Files: 9 files
• Test Files: None

Module Location

src/CrossValidators/

Components to Test

Cross-Validators

• KFoldCrossValidator
• StratifiedKFoldCrossValidator
• GroupKFoldCrossValidator
• LeaveOneOutCrossValidator
• TimeSeriesCrossValidator
• MonteCarloValidator
• NestedCrossValidator
• StandardCrossValidator
• CrossValidatorBase

Test Categories

1. K-Fold Tests

• Verify fold sizes are equal
• Test with different k values
• Verify no data leakage between folds
• Test shuffling behavior

2. Stratified K-Fold Tests

• Verify class proportions preserved
• Test with imbalanced classes
• Compare against scikit-learn

3. Group K-Fold Tests

• Verify groups not split across folds
• Test with varying group sizes

4. Leave-One-Out Tests

• Verify n folds for n samples
• Test computational efficiency

5. Time Series Tests

• Verify temporal ordering preserved
• Test gap and max_train_size
• No future data leakage

6. Nested CV Tests

• Verify inner/outer loop separation
• Test hyperparameter selection
• Verify unbiased evaluation

7. Monte Carlo Tests

• Test random splits
• Verify split ratios
• Test reproducibility with seed

Edge Cases

• Test with very small datasets
• Test with single class (should fail gracefully)
• Test with k > n samples

Acceptance Criteria

• All 9 validators tested
• No data leakage verified
• Fold indices correct
• Compare against scikit-learn
• 80%+ coverage

References

• scikit-learn cross-validation: https://scikit-learn.org/stable/modules/cross_validation.html

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🔗 Similar Issues

Related Issues

• test: Add integration tests for FeatureSelectors module [P1] #624
• test: Add comprehensive integration tests for Clustering module [P0] #617
• test: Add comprehensive integration tests for Regression module [P0] #621
• test: Add integration tests for MetaLearning module [P1] #623

🔗 Related PRs

#259 - feat: Production-Ready Multi-Class Confusion Matrix (Issue #257) [merged]
#338 - Resolve Issue #333 [merged]
#599 - test: add comprehensive mathematical loss function tests [merged]
#608 - test: add comprehensive integration tests for fit detectors [merged]
#610 - test: add integration tests for transfer learning (#360, #361) [closed]

👤 Suggested Assignees

• ooples

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