run-tests: implement Test._testMethodName

This methods is needed internally by utilities like __repr__. I do not see any
harm in having it declared. Any actual attempt to use it to call a test would
crash, but at least random debug print in the test runner will no longer crash.

Another approach would have been to redefine the __repr__ function, but I think
it a good thing to have some respect for the base class API.

tests/run-tests.py

@@ -442,6 +442,11 b' class Test(unittest.TestCase):'
         else:
             self._refout = []
 
+    # needed to get base class __repr__ running
+    @property
+    def _testMethodName(self):
+        return self.name
+
     def __str__(self):
         return self.name