Check python>=2.7 before running tempest

* Tempest requires python>=2.7
* Check python version >=2.7 before installing virtualenv for tempest

Change-Id: I89048652d879fd3907f1628887dd6cc1e6e3ba3e
Closes-Bug: #1336209

rally/exceptions.py

@@ -246,3 +246,8 @@ class UnknownRelease(RallyException):
 
 class ImageCleanUpException(RallyException):
     msg_fmt = _("Image Deletion Failed")
+
+
+class IncompatiblePythonVersion(RallyException):
+    msg_fmt = _("Incompatible python version found '%(version)s', "
+                "required at least python>=2.7.x")

rally/verification/verifiers/tempest/tempest.py

@@ -18,6 +18,7 @@ import logging
 import os
 import shutil
 import subprocess
+import sys
 
 from rally import exceptions
 from rally.openstack.common.gettextutils import _
@@ -63,6 +64,8 @@ class Tempest(object):
 
     def _install_venv(self):
         if not os.path.isdir(os.path.join(self.tempest_path, '.venv')):
+            LOG.info('Validating python environment')
+            self.validate_env()
             LOG.info("No virtual environment found...Install the virtualenv.")
             LOG.debug("Virtual environment directory: %s" %
                       os.path.join(self.tempest_path, ".venv"))
@@ -230,6 +233,14 @@ class Tempest(object):
             self.verification.finish_verification(total=total,
                                                   test_cases=test_cases)
 
+    def validate_env(self):
+        """Validate environment parameters required for running tempest
+           eg: python>2.7
+        """
+        if sys.version_info < (2, 7):
+            raise exceptions.IncompatiblePythonVersion(
+                                                    version=sys.version_info)
+
     def verify(self, set_name, regex):
         self._prepare_and_run(set_name, regex)
         self._save_results()

tests/verification/verifiers/test_tempest.py

@@ -14,9 +14,12 @@
 #    under the License.
 
 import os
+import sys
 
 import mock
+import testtools
 
+from rally import exceptions
 from rally.openstack.common import jsonutils
 from rally.verification.verifiers.tempest import subunit2json
 from rally.verification.verifiers.tempest import tempest
@@ -125,6 +128,7 @@ class TempestTestCase(test.TestCase):
 
     @mock.patch('os.path.isdir')
     @mock.patch(TEMPEST_PATH + '.tempest.subprocess')
+    @testtools.skipIf(sys.version_info < (2, 7), "Incompatible Python Version")
     def test__venv_install_when_venv_exists(self, mock_sp, mock_isdir):
         mock_isdir.return_value = True
         self.verifier._install_venv()
@@ -135,6 +139,7 @@ class TempestTestCase(test.TestCase):
 
     @mock.patch('os.path.isdir')
     @mock.patch(TEMPEST_PATH + '.tempest.subprocess.check_call')
+    @testtools.skipIf(sys.version_info < (2, 7), "Incompatible Python Version")
     def test__venv_install_when_venv_not_exist(self, mock_sp, mock_isdir):
         mock_isdir.return_value = False
         self.verifier._install_venv()
@@ -148,6 +153,17 @@ class TempestTestCase(test.TestCase):
                       self.verifier.venv_wrapper, shell=True,
                       cwd=self.verifier.tempest_path)])
 
+    @mock.patch('os.path.isdir')
+    @testtools.skipIf(sys.version_info >= (2, 7),
+                      "Incompatible Python Version")
+    def test__venv_install_for_py26_fails(self, mock_isdir):
+        mock_isdir.return_value = False
+        self.assertRaises(exceptions.IncompatiblePythonVersion,
+                          self.verifier._install_venv)
+
+        mock_isdir.assert_called_once_with(
+            os.path.join(self.verifier.tempest_path, '.venv'))
+
     @mock.patch('os.path.isdir')
     @mock.patch(TEMPEST_PATH + '.tempest.subprocess')
     def test__initialize_testr_when_testr_already_initialized(