support nose-style `__test__` attribute on modules, classes and

functions, including unittest-style Classes.  If set to True, the
test will not be collected.

--HG--
branch : nose_test_attr

_pytest/python.py

@@ -314,6 +314,9 @@ class PyCollector(PyobjMixin, pytest.Collector):
                 return True
 
     def collect(self):
+        if not getattr(self.obj, "__test__", True):
+            return []
+
         # NB. we avoid random getattrs and peek in the __dict__ instead
         # (XXX originally introduced from a PyPy need, still true?)
         dicts = [getattr(self.obj, '__dict__', {})]

_pytest/unittest.py

@@ -41,10 +41,12 @@ class UnitTestCase(pytest.Class):
         super(UnitTestCase, self).setup()
 
     def collect(self):
+        cls = self.obj
+        if not getattr(cls, "__test__", True):
+            return
         self.session._fixturemanager.parsefactories(self, unittest=True)
         loader = py.std.unittest.TestLoader()
         module = self.getparent(pytest.Module).obj
-        cls = self.obj
         foundsomething = False
         for name in loader.getTestCaseNames(self.obj):
             x = getattr(self.obj, name)