bpo-34596: Fallback to a default reason when @unittest.skip is uncalled (GH-9082) (#15781)

* bpo-34596: Fallback to a default reason when @unittest.skip is uncalled

* Change default reason to empty string

* Fix rst formatting of NEWS entry
(cherry picked from commit d5fd75c53f)

Co-authored-by: Naitree Zhu <Naitreey@gmail.com>

Lib/unittest/case.py

@@ -10,6 +10,7 @@ import warnings
 import collections
 import contextlib
 import traceback
+import types
 
 from . import result
 from .util import (strclass, safe_repr, _count_diff_all_purpose,
@@ -122,6 +123,10 @@ def skip(reason):
         test_item.__unittest_skip__ = True
         test_item.__unittest_skip_why__ = reason
         return test_item
+    if isinstance(reason, types.FunctionType):
+        test_item = reason
+        reason = ''
+        return decorator(test_item)
     return decorator
 
 def skipIf(condition, reason):

Lib/unittest/test/test_skipping.py

@@ -255,6 +255,17 @@ class Test_TestSkipping(unittest.TestCase):
         suite.run(result)
         self.assertEqual(result.skipped, [(test, "testing")])
 
+    def test_skip_without_reason(self):
+        class Foo(unittest.TestCase):
+            @unittest.skip
+            def test_1(self):
+                pass
+
+        result = unittest.TestResult()
+        test = Foo("test_1")
+        suite = unittest.TestSuite([test])
+        suite.run(result)
+        self.assertEqual(result.skipped, [(test, "")])
 
 if __name__ == "__main__":
     unittest.main()

Misc/NEWS.d/next/Tests/2018-09-07-01-18-27.bpo-34596.r2-EGd.rst

@@ -0,0 +1,2 @@
+Fallback to a default reason when :func:`unittest.skip` is uncalled. Patch by
+Naitree Zhu.