ENH: Make warning testing context managers more specific

This means that warnings of different origin then the one tested for
behave normally. If the normal behaviour is to igonre them this might
decrease specificity in rare cases. In most cases the specificity
will be slightly higher.

1 files changed, 5 insertions, 7 deletions

diff --git a/numpy/testing/tests/test_utils.py b/numpy/testing/tests/test_utils.py
index c0f609883..c191aea5b 100644
--- a/numpy/testing/tests/test_utils.py
+++ b/numpy/testing/tests/test_utils.py
@@ -503,23 +503,21 @@ class TestWarns(unittest.TestCase):
             warnings.warn("yo", DeprecationWarning)
 
         failed = False
-        filters = sys.modules['warnings'].filters[:]
-        try:
+        with warnings.catch_warnings():
+            warnings.simplefilter("error", DeprecationWarning)
             try:
-                # Should raise an AssertionError
+                # Should raise a DeprecationWarning
                 assert_warns(UserWarning, f)
                 failed = True
-            except AssertionError:
+            except DeprecationWarning:
                 pass
-        finally:
-            sys.modules['warnings'].filters = filters
 
         if failed:
             raise AssertionError("wrong warning caught by assert_warn")
 
 
 class TestAssertAllclose(unittest.TestCase):
-    
+
     def test_simple(self):
         x = 1e-3
         y = 1e-9