Issue 7911: unittest.TestCase.longMessage defaults to True for improved failure messages by default

Doc/library/unittest.rst

@@ -1305,8 +1305,8 @@ Test cases
       to ``True`` allows you to have a custom error message in addition to the
       normal one.
 
-      This attribute defaults to ``False``, meaning that a custom message passed
-      to an assert method will silence the normal message.
+      This attribute defaults to ``True``. If set to False then a custom message
+      passed to an assert method will silence the normal message.
 
       The class setting can be overridden in individual tests by assigning an
       instance attribute to ``True`` or ``False`` before calling the assert methods.

Lib/unittest/case.py

@@ -245,7 +245,7 @@ class TestCase(object):
     # objects used in assert methods) will be printed on failure in *addition*
     # to any explicit message passed.
 
-    longMessage = False
+    longMessage = True
 
     # This attribute sets the maximum length of a diff in failure messages
     # by assert methods using difflib. It is looked up as an instance attribute

Lib/unittest/test/test_assertions.py

@@ -127,7 +127,7 @@ class TestLongMessage(unittest.TestCase):
         self.testableFalse = TestableTestFalse('testTest')
 
     def testDefault(self):
-        self.assertFalse(unittest.TestCase.longMessage)
+        self.assertTrue(unittest.TestCase.longMessage)
 
     def test_formatMsg(self):
         self.assertEqual(self.testableFalse._formatMessage(None, "foo"), "foo")

Misc/NEWS

@@ -10,6 +10,9 @@ What's New in Python 3.2 Beta 1?
 Core and Builtins
 -----------------
 
+- Issue 7911: `unittest.TestCase.longMessage` defaults to True for improved
+  failure messages by default. Patch by Mark Roddy.
+  
 - Issue #9915: Speed up sorting with a key.
 
 - Issue #9333: Expose os.symlink only when the SeCreateSymbolicLinkPrivilege