troubleshooting for CI tests for #19304

bsun94 · bsun94 · commit fd242b7fe865 · 2021-04-11T18:52:46.000-04:00
diff --git a/doc/whats_new/v1.0.rst b/doc/whats_new/v1.0.rst
@@ -163,8 +163,8 @@ Changelog
   :pr:`19564` by `Thomas Fan`_.
 
 - |Enhancement| Documented and tested support of the Poisson criterion for
-:class:`ensemble.RandomForestRegressor`. :pr:`19836` by
-:user:`Brian Sun <bsun94>`.
+  :class:`ensemble.RandomForestRegressor`. :pr:`19836` by
+  :user:`Brian Sun <bsun94>`.
 
 :mod:`sklearn.feature_extraction`
 .................................
diff --git a/sklearn/ensemble/tests/test_forest.py b/sklearn/ensemble/tests/test_forest.py
@@ -1358,24 +1358,24 @@ def test_min_impurity_decrease():
             # will suffice for the actual working of this param
             assert tree.min_impurity_decrease == 0.1
 
+
 def test_poisson_y_positive_check():
     est = RandomForestRegressor(criterion="poisson")
     X = np.zeros((3, 3))
 
     y = [-1, 1, 3]
-    with pytest.raises(
-        ValueError,
-        match="Some.*y are negative.*Poisson.*\."
-    ):
+    err_msg = (r"Some value\(s\) of y are negative which is "
+               r"not allowed for Poisson regression.")
+    with pytest.raises(ValueError, match=err_msg):
         est.fit(X, y)
 
     y = [0, 0, 0]
-    with pytest.raises(
-        ValueError,
-        match="Sum of y is not positive.*Poisson regression\."
-    ):
+    err_msg = (r"Sum of y is not strictly positive which "
+               r"is necessary for Poisson regression.")
+    with pytest.raises(ValueError, match=err_msg):
         est.fit(X, y)
 
+
 # mypy error: Variable "DEFAULT_JOBLIB_BACKEND" is not valid type
 class MyBackend(DEFAULT_JOBLIB_BACKEND):  # type: ignore
     def __init__(self, *args, **kwargs):
