Remove the use of assert_raises and assert_raises_regex from the tests

~(Saving this for the upcoming sprints, ideally)~

Let’s remove the use of assert_raises, assert_raise_message, and assert_raises_regex.

These should be replaced with the pytest context manager:

with pytest.raises(TheException, match="the expected message"):
   function_call_here()

(no need for match in the case of assert_raises and assert_raise_message I guess).

For contributors: pick one of the modules below, and please comment on this issue saying e.g. “I’m working on cluster/tests”, to avoid other contributors choosing the same modules.

You can see all the occurrences of the entries that need to be removed with e.g. git grep "assert_raises" sklearn/ensemble/tests/.

Modules that need cleaning

• sklearn/cluster/tests/ #14649)
• sklearn/compose/tests/ #14670
• sklearn/covariance/tests/ #14674
• sklearn/datasets/tests/ #14676
• sklearn/decomposition/tests/ #14679
• sklearn/ensemble/tests/ #19399
• sklearn/feature_extraction/tests/ #14694
• sklearn/feature_selection/tests/ #14697
• sklearn/linear_model/tests/ #19440
• sklearn/manifold/tests/ #14699
• sklearn/metrics/cluster/tests/ #14707
• sklearn/metrics/tests/ #14715
• sklearn/model_selection/tests/ #19592
• sklearn/neighbors/tests/ #19388
• sklearn/neural_network/tests/ #14716
• sklearn/preprocessing/tests/ #14717
• sklearn/semi_supervised/tests/ #14841
• sklearn/svm/tests/ #14727
• sklearn/tests/ #19500
• sklearn/tree/tests/ #14737
• sklearn/utils/estimator_checks.py
• sklearn/utils/tests/ #16337

Some more:

• sklearn/metrics/cluster/tests/test_unsupervised.py see #20065
• sklearn/compose/tests/test_column_transformer.py
• sklearn/covariance/tests/test_robust_covariance.py
• sklearn/datasets/tests/test_openml.py
• sklearn/datasets/tests/test_samples_generator.py
• sklearn/decomposition/tests/test_nmf.py
• sklearn/decomposition/tests/test_factor_analysis.py
• sklearn/feature_extraction/tests/test_text.py
• sklearn/linear_model/tests/test_bayes.py
• sklearn/linear_model/tests/test_sag.py
• sklearn/linear_model/tests/test_ransac.py
• sklearn/manifold/tests/test_locally_linear.py
• sklearn/metrics/cluster/tests/test_unsupervised.py
• sklearn/mixture/tests/test_bayesian_mixture.py
• sklearn/mixture/tests/test_gaussian_mixture.py
• sklearn/svm/tests/test_bounds.py
• sklearn/svm/tests/test_sparse.py
• sklearn/svm/tests/test_svm.py
• sklearn/tests/test_base.py
• sklearn/tests/test_isotonic.py

Also:

• sklearn/utils/tests/test_estimator_checks.py but this should use the custom raises CM in sklearn/utils/_testing.py instead, as we don’t want to use pytest for this file

[lorentzenchr]

I also don’t find any left overs. As discussed, the exception is sklearn/utils/estimator_checks.py (and dependendies) where we do not want to depend on pytest.

A Great Thank You to all contributors!

[azihna]

@NicolasHug the test_estimator_checks are also cleaned.