Run tests only if Python2 is used, print warning otherwise.

caucase/test.py

@@ -2882,4 +2882,8 @@ if getattr(CaucaseTest, 'assertItemsEqual', None) is None: # pragma: no cover
 # pylint: enable=no-member
 
 if __name__ == '__main__': # pragma: no cover
-  unittest.main()
+  if sys.version_info.major == 2:
+    # currently we support only Python2
+    unittest.main()
+  else:
+    print "caucase supports only Python2."

[Jérome Perrin]

[ continuing nexedi/slapos.buildout!19 (comment 96171) ]

I think your idea to "disable" test directly in the python code and not in buildout makes sense. I feel we can use unittest "skip" here, it's also supported in our test integration. I see we can use a skipIf decorator on the class, so maybe we can put it on the CaucaseTest class, for example:

import unittest
import sys

@unittest.skipIf(sys.version_info >= (3, ), 'Caucase currently supports python 2 only')
class Test(unittest.TestCase):
    def test_a(self):
        self.assertEqual('a', 'A')
    def test_b(self):
        self.assertEqual('b', 'B')

$ python2 -m unittest test
FF
======================================================================
FAIL: test_a (test.Test)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "test.py", line 7, in test_a
    self.assertEqual('a', 'A')
AssertionError: 'a' != 'A'

======================================================================
FAIL: test_b (test.Test)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "test.py", line 9, in test_b
    self.assertEqual('b', 'B')
AssertionError: 'b' != 'B'

----------------------------------------------------------------------
Ran 2 tests in 0.000s

FAILED (failures=2)
$ python3 -m unittest test
ss
----------------------------------------------------------------------
Ran 2 tests in 0.000s

OK (skipped=2)

/cc @vpelletier @luke

PS: To apply the same on kedifa it's a bit more complex because caucase uses some python2 only syntax, but it's maybe only with print. When using from __future__ import print_function then python2's print behaves same as python3's one so that could be a way. It was done in jerome/kedifa@0ffdfacf , with lots of other "not ready" changes .