Implement pytest.deprecated_call with pytest.warns

changelog/4102.feature.rst

@@ -0,0 +1 @@
+Reimplement ``pytest.deprecated_call`` using ``pytest.warns`` so it supports the ``match='...'`` keyword argument.

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:

testing/test_recwarn.py

@@ -76,9 +76,8 @@ class TestDeprecatedCall(object):
             )
 
     def test_deprecated_call_raises(self):
-        with pytest.raises(AssertionError) as excinfo:
+        with pytest.raises(pytest.fail.Exception, match="No warnings of type"):
             pytest.deprecated_call(self.dep, 3, 5)
-        assert "Did not produce" in str(excinfo)
 
     def test_deprecated_call(self):
         pytest.deprecated_call(self.dep, 0, 5)
@@ -100,7 +99,7 @@ class TestDeprecatedCall(object):
         assert warn_explicit is warnings.warn_explicit
 
     def test_deprecated_explicit_call_raises(self):
-        with pytest.raises(AssertionError):
+        with pytest.raises(pytest.fail.Exception):
             pytest.deprecated_call(self.dep_explicit, 3)
 
     def test_deprecated_explicit_call(self):
@@ -116,8 +115,8 @@ class TestDeprecatedCall(object):
         def f():
             pass
 
-        msg = "Did not produce DeprecationWarning or PendingDeprecationWarning"
-        with pytest.raises(AssertionError, match=msg):
+        msg = "No warnings of type (.*DeprecationWarning.*, .*PendingDeprecationWarning.*)"
+        with pytest.raises(pytest.fail.Exception, match=msg):
             if mode == "call":
                 pytest.deprecated_call(f)
             else:
@@ -179,12 +178,20 @@ class TestDeprecatedCall(object):
             def f():
                 warnings.warn(warning("hi"))
 
-            with pytest.raises(AssertionError):
+            with pytest.raises(pytest.fail.Exception):
                 pytest.deprecated_call(f)
-            with pytest.raises(AssertionError):
+            with pytest.raises(pytest.fail.Exception):
                 with pytest.deprecated_call():
                     f()
 
+    def test_deprecated_call_supports_match(self):
+        with pytest.deprecated_call(match=r"must be \d+$"):
+            warnings.warn("value must be 42", DeprecationWarning)
+
+        with pytest.raises(pytest.fail.Exception):
+            with pytest.deprecated_call(match=r"must be \d+$"):
+                warnings.warn("this is not here", DeprecationWarning)
+
 
 class TestWarns(object):
     def test_strings(self):