Use assert_raises_regexp to check error messages

Author: AlexanderFabisch

sklearn/metrics/tests/test_score_objects.py

@@ -4,7 +4,7 @@
 
 from sklearn.utils.testing import assert_almost_equal
 from sklearn.utils.testing import assert_raises
-from sklearn.utils.testing import assert_raise_message
+from sklearn.utils.testing import assert_raises_regexp
 from sklearn.utils.testing import assert_true
 from sklearn.utils.testing import ignore_warnings
 
@@ -58,7 +58,9 @@ def predict(self, X):
 def test_check_scoring():
     """Test all branches of check_scoring"""
     estimator = EstimatorWithoutFit()
-    assert_raise_message(TypeError, "'fit' method", check_scoring, estimator)
+    assert_raises_regexp(TypeError,
+        r"estimator should a be an estimator implementing 'fit' method, .* "
+        "was passed", check_scoring, estimator)
 
     estimator = EstimatorWithFitAndScore()
     estimator.fit([[1]], [1])
@@ -67,14 +69,17 @@ def test_check_scoring():
 
     estimator = EstimatorWithFitAndPredict()
     estimator.fit([[1]], [1])
-    assert_raise_message(TypeError, "no scoring", check_scoring, estimator)
+    assert_raises_regexp(TypeError,
+        r"If no scoring is specified, the estimator passed should have a "
+        "'score' method\. The estimator .* does not.", check_scoring, estimator)
 
     scorer = check_scoring(estimator, "accuracy")
     assert_almost_equal(scorer(estimator, [[1]], [1]), 1.0)
 
     estimator = EstimatorWithFit()
-    assert_raise_message(TypeError, "'score' or a 'predict'", check_scoring,
-                         estimator, "accuracy")
+    assert_raises_regexp(TypeError,
+        r"The estimator passed should have a 'score' or a 'predict' method. "
+        "The estimator .* does not.", check_scoring, estimator, "accuracy")
 
     estimator = EstimatorWithFit()
     scorer = check_scoring(estimator, allow_none=True)

sklearn/utils/testing.py

@@ -34,6 +34,7 @@
 from nose.tools import assert_true
 from nose.tools import assert_false
 from nose.tools import assert_raises
+from nose.tools import assert_raises_regexp
 from nose.tools import raises
 from nose import SkipTest
 from nose import with_setup
@@ -47,10 +48,10 @@
 from sklearn.base import (ClassifierMixin, RegressorMixin, TransformerMixin,
                           ClusterMixin)
 
-__all__ = ["assert_equal", "assert_not_equal", "assert_raises", "raises",
-           "with_setup", "assert_true", "assert_false", "assert_almost_equal",
-           "assert_array_equal", "assert_array_almost_equal",
-           "assert_array_less"]
+__all__ = ["assert_equal", "assert_not_equal", "assert_raises",
+           "assert_raises_regexp", "raises", "with_setup", "assert_true",
+           "assert_false", "assert_almost_equal", "assert_array_equal",
+           "assert_array_almost_equal", "assert_array_less"]
 
 
 try: