Merge pull request #4104 from asottile/deprecated_call_match

Implement pytest.deprecated_call with pytest.warns

src/_pytest/recwarn.py

@@ -43,45 +43,10 @@ def deprecated_call(func=None, *args, **kwargs):
     in which case it will ensure calling ``func(*args, **kwargs)`` produces one of the warnings
     types above.
     """
-    if not func:
-        return _DeprecatedCallContext()
-    else:
-        __tracebackhide__ = True
-        with _DeprecatedCallContext():
-            return func(*args, **kwargs)
-
-
-class _DeprecatedCallContext(object):
-    """Implements the logic to capture deprecation warnings as a context manager."""
-
-    def __enter__(self):
-        self._captured_categories = []
-        self._old_warn = warnings.warn
-        self._old_warn_explicit = warnings.warn_explicit
-        warnings.warn_explicit = self._warn_explicit
-        warnings.warn = self._warn
-
-    def _warn_explicit(self, message, category, *args, **kwargs):
-        self._captured_categories.append(category)
-
-    def _warn(self, message, category=None, *args, **kwargs):
-        if isinstance(message, Warning):
-            self._captured_categories.append(message.__class__)
-        else:
-            self._captured_categories.append(category)
-
-    def __exit__(self, exc_type, exc_val, exc_tb):
-        warnings.warn_explicit = self._old_warn_explicit
-        warnings.warn = self._old_warn
-
-        if exc_type is None:
-            deprecation_categories = (DeprecationWarning, PendingDeprecationWarning)
-            if not any(
-                issubclass(c, deprecation_categories) for c in self._captured_categories
-            ):
-                __tracebackhide__ = True
-                msg = "Did not produce DeprecationWarning or PendingDeprecationWarning"
-                raise AssertionError(msg)
+    __tracebackhide__ = True
+    if func is not None:
+        args = (func,) + args
+    return warns((DeprecationWarning, PendingDeprecationWarning), *args, **kwargs)
 
 
 def warns(expected_warning, *args, **kwargs):
@@ -116,6 +81,7 @@ def warns(expected_warning, *args, **kwargs):
         Failed: DID NOT WARN. No warnings of type ...UserWarning... was emitted...
 
     """
+    __tracebackhide__ = True
     match_expr = None
     if not args:
         if "match" in kwargs:
@@ -183,12 +149,25 @@ class WarningsRecorder(warnings.catch_warnings):
             raise RuntimeError("Cannot enter %r twice" % self)
         self._list = super(WarningsRecorder, self).__enter__()
         warnings.simplefilter("always")
+        # python3 keeps track of a "filter version", when the filters are
+        # updated previously seen warnings can be re-warned.  python2 has no
+        # concept of this so we must reset the warnings registry manually.
+        # trivial patching of `warnings.warn` seems to be enough somehow?
+        if six.PY2:
+
+            def warn(*args, **kwargs):
+                return self._saved_warn(*args, **kwargs)
+
+            warnings.warn, self._saved_warn = warn, warnings.warn
         return self
 
     def __exit__(self, *exc_info):
         if not self._entered:
             __tracebackhide__ = True
             raise RuntimeError("Cannot exit %r without entering first" % self)
+        # see above where `self._saved_warn` is assigned
+        if six.PY2:
+            warnings.warn = self._saved_warn
         super(WarningsRecorder, self).__exit__(*exc_info)