gbrt: min_weight_fraction_leaf value test

Author: ndawe

sklearn/ensemble/tests/test_gradient_boosting.py

@@ -87,6 +87,13 @@ def test_parameter_checks():
     assert_raises(ValueError,
                   GradientBoostingClassifier(min_samples_leaf=-1.).fit, X, y)
 
+    assert_raises(ValueError,
+                  GradientBoostingClassifier(min_weight_fraction_leaf=-1.).fit,
+                  X, y)
+    assert_raises(ValueError,
+                  GradientBoostingClassifier(min_weight_fraction_leaf=0.6).fit,
+                  X, y)
+
     assert_raises(ValueError,
                   GradientBoostingClassifier(subsample=0.0).fit, X, y)
     assert_raises(ValueError,