FIXUP: as per Bruno's suggestions

_pytest/python.py

@@ -1168,6 +1168,22 @@ def __exit__(self, *tp):
 # builtin pytest.warns helper
 
 def warns(ExpectedWarning, *args, **kwargs):
+    """Assert that code raises a particular class of warning.
+
+    Specifically, the input ``ExpectedWarning`` can be a warning class or
+    tuple of warning classes, and the code must return that warning
+    (if a single class) or one of those warnings (if a tuple).
+
+    This helper produces a list of ``warnings.WarningMessage`` objects,
+    one for each warning raised.
+
+    This function can be used as a context manager, or any of the other ways
+    ``pytest.raises`` can be used::
+
+        >>> with warns(RuntimeWarning):
+        ...    warnings.warn("my warning", RuntimeWarning)
+    """
+
     msg = ("exceptions must be old-style classes or"
            " derived from Warning, not %s")
     if isinstance(ExpectedWarning, tuple):
@@ -1213,7 +1229,7 @@ def __enter__(self):
     def __exit__(self, type, value, traceback):
         self.catcher.__exit__(type, value, traceback)
         if not any(r.category in self.ExpectedWarning for r in self.record):
-            pytest.fail("DID NOT RAISE")
+            pytest.fail("DID NOT WARN")
 
 #
 #  the basic pytest Function item
@@ -2175,4 +2191,3 @@ def get_scope_node(node, scope):
             return node.session
         raise ValueError("unknown scope")
     return node.getparent(cls)
-

testing/python/raises.py

@@ -34,7 +34,6 @@ def test_raises_flip_builtin_AssertionError(self):
             raise BuiltinAssertionError
         """)
 
-    @pytest.mark.skipif('sys.version < "2.5"')
     def test_raises_as_contextmanager(self, testdir):
         testdir.makepyfile("""
             from __future__ import with_statement

testing/python/warns.py

@@ -26,7 +26,6 @@ def test_warns_tuple(self):
                           (RuntimeWarning, SyntaxWarning),
                           lambda: warnings.warn('w3', UserWarning)))
 
-    @pytest.mark.skipif('sys.version < "2.5"')
     def test_warns_as_contextmanager(self, testdir):
         with pytest.warns(RuntimeWarning):
             warnings.warn("runtime", RuntimeWarning)