Handle case without pytest for plugin tests

Switching the test runner to pytest in horizon assumes pytest is always
installed, but horizon test helpers are used in horizon plugin tests and
pytest is not used in horizon plugin tests. As a result, all horizon plugin
tests are now broken.

This commit considers a case where pytest does not exist.
A wrapper decorator for pytest.mark.xxxx is introduced and
it acts as a null decorator if pytest is not installed.

Change-Id: I80736b108f5ae9a36c0e756bf386468879be3293
Closes-Bug: #1873532

horizon/test/helpers.py

@@ -21,6 +21,7 @@ import copy
 import logging
 import os
 import socket
+import sys
 import time
 import unittest
 
@@ -42,8 +43,12 @@ from django.utils.encoding import force_text
 from django.contrib.staticfiles.testing \
     import StaticLiveServerTestCase as LiveServerTestCase
 
-import pytest
-
+# horizon plugins does not require pytest, so we need to consider
+# pytest is not installed.
+try:
+    import pytest
+except ImportError:
+    pass
 
 from horizon import middleware
 
@@ -69,6 +74,17 @@ except ImportError as e:
 wsgi.WSGIRequest.__repr__ = lambda self: "<class 'django.http.HttpRequest'>"
 
 
+def pytest_mark(name):
+    if 'pytest' in sys.modules:
+        return getattr(pytest.mark, name)
+    else:
+        # When pytest is not installed (in case of horizon plugins),
+        # we don't need a pytest marker, so just use a null decorator.
+        def wrapper(f):
+            return f
+        return wrapper
+
+
 class SessionStore(SessionBase):
     """Dict like object for simulating sessions in unittests."""
 
@@ -221,7 +237,7 @@ class TestCase(django_test.TestCase):
                                                      ", ".join(msgs))
 
 
-@pytest.mark.selenium
+@pytest_mark('selenium')
 @tag('selenium')
 class SeleniumTestCase(LiveServerTestCase):
     @classmethod

openstack_dashboard/test/helpers.py

@@ -33,7 +33,6 @@ from django.utils import http
 
 from openstack_auth import user
 from openstack_auth import utils
-import pytest
 from requests.packages.urllib3.connection import HTTPConnection
 
 from horizon import base
@@ -472,7 +471,7 @@ class ResetImageAPIVersionMixin(object):
         super(ResetImageAPIVersionMixin, self).tearDown()
 
 
-@pytest.mark.selenium
+@horizon_helpers.pytest_mark('selenium')
 @tag('selenium')
 class SeleniumTestCase(horizon_helpers.SeleniumTestCase):
 
@@ -540,7 +539,7 @@ def my_custom_sort(flavor):
 # PluginTestCase as a separate test process. Hopefully this workaround has gone
 # in future. For more detail, see bugs 1809983, 1866666 and
 # https://review.opendev.org/#/c/627640/.
-@pytest.mark.plugin_test
+@horizon_helpers.pytest_mark('plugin_test')
 @tag('plugin-test')
 class PluginTestCase(TestCase):
     """Test case for testing plugin system of Horizon.

openstack_dashboard/test/integration_tests/helpers.py

@@ -23,13 +23,13 @@ import traceback
 
 from django.test import tag
 from oslo_utils import uuidutils
-import pytest
 from selenium.webdriver.common import action_chains
 from selenium.webdriver.common import by
 from selenium.webdriver.common import keys
 import testtools
 import xvfbwrapper
 
+from horizon.test import helpers
 from horizon.test import webdriver
 from openstack_dashboard.test.integration_tests import config
 from openstack_dashboard.test.integration_tests.pages import loginpage
@@ -103,7 +103,7 @@ class AssertsMixin(object):
         return self.assertEqual(list(actual), [False] * len(actual))
 
 
-@pytest.mark.integration
+@helpers.pytest_mark('integration')
 @tag('integration')
 class BaseTestCase(testtools.TestCase):
 
@@ -307,7 +307,7 @@ class BaseTestCase(testtools.TestCase):
         return html_elem.get_attribute("innerHTML").encode("utf-8")
 
 
-@pytest.mark.integration
+@helpers.pytest_mark('integration')
 @tag('integration')
 class TestCase(BaseTestCase, AssertsMixin):