diff options
| -rw-r--r-- | Lib/test/test_warnings.py | 35 | ||||
| -rw-r--r-- | Lib/warnings.py | 4 | ||||
| -rw-r--r-- | Misc/NEWS | 3 | ||||
| -rw-r--r-- | Python/_warnings.c | 13 |
4 files changed, 48 insertions, 7 deletions
diff --git a/Lib/test/test_warnings.py b/Lib/test/test_warnings.py index cf7f747753..cd3288b6b5 100644 --- a/Lib/test/test_warnings.py +++ b/Lib/test/test_warnings.py @@ -370,6 +370,41 @@ class WarnTests(BaseTest): with self.assertRaises(ValueError): self.module.warn(BadStrWarning()) + def test_warning_classes(self): + class MyWarningClass(Warning): + pass + + class NonWarningSubclass: + pass + + # passing a non-subclass of Warning should raise a TypeError + with self.assertRaises(TypeError) as cm: + self.module.warn('bad warning category', '') + self.assertIn('category must be a Warning subclass, not ', + str(cm.exception)) + + with self.assertRaises(TypeError) as cm: + self.module.warn('bad warning category', NonWarningSubclass) + self.assertIn('category must be a Warning subclass, not ', + str(cm.exception)) + + # check that warning instances also raise a TypeError + with self.assertRaises(TypeError) as cm: + self.module.warn('bad warning category', MyWarningClass()) + self.assertIn('category must be a Warning subclass, not ', + str(cm.exception)) + + with self.assertWarns(MyWarningClass) as cm: + self.module.warn('good warning category', MyWarningClass) + self.assertEqual('good warning category', str(cm.warning)) + + with self.assertWarns(UserWarning) as cm: + self.module.warn('good warning category', None) + self.assertEqual('good warning category', str(cm.warning)) + + with self.assertWarns(MyWarningClass) as cm: + self.module.warn('good warning category', MyWarningClass) + self.assertIsInstance(cm.warning, Warning) class CWarnTests(WarnTests, unittest.TestCase): module = c_warnings diff --git a/Lib/warnings.py b/Lib/warnings.py index a427e3510e..f37b8a771a 100644 --- a/Lib/warnings.py +++ b/Lib/warnings.py @@ -162,7 +162,9 @@ def warn(message, category=None, stacklevel=1): # Check category argument if category is None: category = UserWarning - assert issubclass(category, Warning) + if not (isinstance(category, type) and issubclass(category, Warning)): + raise TypeError("category must be a Warning subclass, " + "not '{:s}'".format(type(category).__name__)) # Get context information try: caller = sys._getframe(stacklevel) @@ -108,6 +108,9 @@ Core and Builtins Library ------- +- Issue #16382: Improve exception message of warnings.warn() for bad + category. Initial patch by Phil Elson. + - Issue #21932: os.read() now uses a :c:func:`Py_ssize_t` type instead of :c:type:`int` for the size to support reading more than 2 GB at once. On Windows, the size is truncted to INT_MAX. As any call to os.read(), the OS diff --git a/Python/_warnings.c b/Python/_warnings.c index 6013d7d7d4..363c1f29bb 100644 --- a/Python/_warnings.c +++ b/Python/_warnings.c @@ -619,16 +619,17 @@ get_category(PyObject *message, PyObject *category) if (rc == 1) category = (PyObject*)message->ob_type; - else if (category == NULL) + else if (category == NULL || category == Py_None) category = PyExc_UserWarning; /* Validate category. */ rc = PyObject_IsSubclass(category, PyExc_Warning); - if (rc == -1) - return NULL; - if (rc == 0) { - PyErr_SetString(PyExc_ValueError, - "category is not a subclass of Warning"); + /* category is not a subclass of PyExc_Warning or + PyObject_IsSubclass raised an error */ + if (rc == -1 || rc == 0) { + PyErr_Format(PyExc_TypeError, + "category must be a Warning subclass, not '%s'", + Py_TYPE(category)->tp_name); return NULL; } |