TST: do not use "ignore" to filter warnings

seberg · seberg · commit fd399aaee5b7 · 2014-02-21T21:13:29.000+01:00
When a warning is ignored (or raised once) in python, the warnings module will tag on a `__warningregistry__` dictionary to be able to filter these warnings in the future. This is tagged on to the current context, causing leakage to later calls (this is a bit more complex, since where the registry ends up depends on the layers between the original caller and warner). In short, tests should typically not use ignore but catch the warnings to avoid changing the user experience (or errors on duplicate test runs). Fixes an error on duplicate test runs (does not remove all "ignores" which may change behaviour outside tests). Closes gh-4340
diff --git a/numpy/lib/tests/test_function_base.py b/numpy/lib/tests/test_function_base.py
@@ -1222,8 +1222,8 @@ def test_xy(self):
         assert_allclose(np.corrcoef(x, y), np.array([[1., -1.j], [1.j, 1.]]))
 
     def test_empty(self):
-        with warnings.catch_warnings():
-            warnings.simplefilter('ignore', RuntimeWarning)
+        with warnings.catch_warnings(record=True):
+            warnings.simplefilter('always', RuntimeWarning)
             assert_array_equal(corrcoef(np.array([])), np.nan)
             assert_array_equal(corrcoef(np.array([]).reshape(0, 2)),
                                np.array([]).reshape(0, 0))
@@ -1232,8 +1232,8 @@ def test_empty(self):
 
     def test_wrong_ddof(self):
         x = np.array([[0, 2], [1, 1], [2, 0]]).T
-        with warnings.catch_warnings():
-            warnings.simplefilter('ignore', RuntimeWarning)
+        with warnings.catch_warnings(record=True):
+            warnings.simplefilter('always', RuntimeWarning)
             assert_array_equal(corrcoef(x, ddof=5),
                                np.array([[np.nan, np.nan], [np.nan, np.nan]]))
 
@@ -1253,8 +1253,8 @@ def test_xy(self):
         assert_allclose(cov(x, y), np.array([[1., -1.j], [1.j, 1.]]))
 
     def test_empty(self):
-        with warnings.catch_warnings():
-            warnings.simplefilter('ignore', RuntimeWarning)
+        with warnings.catch_warnings(record=True):
+            warnings.simplefilter('always', RuntimeWarning)
             assert_array_equal(cov(np.array([])), np.nan)
             assert_array_equal(cov(np.array([]).reshape(0, 2)),
                                np.array([]).reshape(0, 0))
@@ -1263,8 +1263,8 @@ def test_empty(self):
 
     def test_wrong_ddof(self):
         x = np.array([[0, 2], [1, 1], [2, 0]]).T
-        with warnings.catch_warnings():
-            warnings.simplefilter('ignore', RuntimeWarning)
+        with warnings.catch_warnings(record=True):
+            warnings.simplefilter('always', RuntimeWarning)
             assert_array_equal(cov(x, ddof=5),
                                np.array([[np.inf, -np.inf], [-np.inf, np.inf]]))
 
diff --git a/numpy/lib/tests/test_nanfunctions.py b/numpy/lib/tests/test_nanfunctions.py
@@ -130,8 +130,8 @@ def test_mutation(self):
     def test_result_values(self):
         for f, fcmp in zip(self.nanfuncs, [np.greater, np.less]):
             for row in _ndat:
-                with warnings.catch_warnings():
-                    warnings.simplefilter('ignore')
+                with warnings.catch_warnings(record=True):
+                    warnings.simplefilter('always')
                     ind = f(row)
                     val = row[ind]
                     # comparing with NaN is tricky as the result
