Windows: fix flaky tests

Some tests compare timestamps (e.g. image created_at/updated_at
fields).

In some cases, subsequent timestamps may be identical, breaking the
assertions made by those tests.

One idea is to just add a 1ms sleep which should be a negligeable.
Mocking the functions used to retrieve timestamps may be undesireable.

For now, we'll do this only for Windows, where time.time has a lower
resolution compared to Linux (1e-7 as opposed to 1e-9).

At the same time, socket timeouts are rather inconsistent on Windows.
When a timeout is hit, recv may either throw ConnectionAbortedError
*or* return nothing. This needs to be taken into account when
expecting socket timeouts.

Change-Id: Ie5a4d8fb4c979c09eda2fdc0fad0baa1d1840c59

glance/tests/functional/db/base.py

@@ -17,7 +17,6 @@
 
 import copy
 import datetime
-import time
 import uuid
 
 import mock
@@ -139,6 +138,7 @@ class TestDriver(test_utils.BaseTestCase):
     def create_images(self, images):
         for fixture in images:
             self.db_api.image_create(self.adm_context, fixture)
+            self.delay_inaccurate_clock()
 
 
 class DriverTests(object):
@@ -319,6 +319,7 @@ class DriverTests(object):
 
     def test_image_update_properties(self):
         fixture = {'properties': {'ping': 'pong'}}
+        self.delay_inaccurate_clock()
         image = self.db_api.image_update(self.adm_context, UUID1, fixture)
         expected = {'ping': 'pong', 'foo': 'bar', 'far': 'boo'}
         actual = {p['name']: p['value'] for p in image['properties']}
@@ -1298,6 +1299,7 @@ class DriverTests(object):
                     'deleted': False}
         self.assertEqual(expected, member)
 
+        self.delay_inaccurate_clock()
         member = self.db_api.image_member_update(self.context,
                                                  member_id,
                                                  {'can_share': True})
@@ -1341,10 +1343,7 @@ class DriverTests(object):
                     'deleted': False}
         self.assertEqual(expected, member)
 
-        # The clock may not be very accurate, for which reason we may
+        self.delay_inaccurate_clock()
-        # get identical timestamps.
-        time.sleep(0.01)
-
         member = self.db_api.image_member_update(self.context,
                                                  member_id,
                                                  {'status': 'accepted'})
@@ -1872,6 +1871,7 @@ class TaskTests(test_utils.BaseTestCase):
             'status': 'processing',
             'message': 'This is a error string',
         }
+        self.delay_inaccurate_clock()
         task = self.db_api.task_update(self.adm_context, task_id, fixture)
 
         self.assertEqual(task_id, task['id'])
@@ -1897,6 +1897,7 @@ class TaskTests(test_utils.BaseTestCase):
 
         task_id = task['id']
         fixture = {'status': 'processing'}
+        self.delay_inaccurate_clock()
         task = self.db_api.task_update(self.adm_context, task_id, fixture)
 
         self.assertEqual(task_id, task['id'])

glance/tests/functional/test_wsgi.py

@@ -44,18 +44,20 @@ class TestWSGIServer(testtools.TestCase):
         port = server.sock.getsockname()[1]
 
         def get_request(delay=0.0):
+            # Socket timeouts are handled rather inconsistently on Windows.
+            # recv may either return nothing OR raise a ConnectionAbortedError.
+            exp_exc = OSError if os.name == 'nt' else ()
+
+            try:
                 sock = socket.socket()
                 sock.connect(('127.0.0.1', port))
                 time.sleep(delay)
                 sock.send(b'GET / HTTP/1.1\r\nHost: localhost\r\n\r\n')
                 return sock.recv(1024)
+            except exp_exc:
+                return None
 
         # Should succeed - no timeout
         self.assertIn(greetings, get_request())
         # Should fail - connection timed out so we get nothing from the server
-        if os.name == 'nt':
-            self.assertRaises(ConnectionAbortedError,
-                              get_request,
-                              delay=1.1)
-        else:
         self.assertFalse(get_request(delay=1.1))

glance/tests/unit/test_db.py

@@ -377,6 +377,7 @@ class TestImageRepo(test_utils.BaseTestCase):
         original_update_time = image.updated_at
         image.name = 'foo'
         image.tags = ['king', 'kong']
+        self.delay_inaccurate_clock()
         self.image_repo.save(image)
         current_update_time = image.updated_at
         self.assertGreater(current_update_time, original_update_time)
@@ -396,6 +397,7 @@ class TestImageRepo(test_utils.BaseTestCase):
     def test_remove_image(self):
         image = self.image_repo.get(UUID1)
         previous_update_time = image.updated_at
+        self.delay_inaccurate_clock()
         self.image_repo.remove(image)
         self.assertGreater(image.updated_at, previous_update_time)
         self.assertRaises(exception.ImageNotFound, self.image_repo.get, UUID1)
@@ -756,6 +758,7 @@ class TestTaskRepo(test_utils.BaseTestCase):
     def test_save_task(self):
         task = self.task_repo.get(UUID1)
         original_update_time = task.updated_at
+        self.delay_inaccurate_clock()
         self.task_repo.save(task)
         current_update_time = task.updated_at
         self.assertGreater(current_update_time, original_update_time)

glance/tests/unit/test_image_cache.py

@@ -135,6 +135,7 @@ class ImageCacheTestCase(object):
 
         self.assertTrue(os.path.exists(incomplete_file_path))
 
+        self.delay_inaccurate_clock()
         self.cache.clean(stall_time=0)
 
         self.assertFalse(os.path.exists(incomplete_file_path))

glance/tests/utils.py

@@ -23,6 +23,7 @@ import shutil
 import socket
 import subprocess
 import threading
+import time
 
 from alembic import command as alembic_command
 import fixtures
@@ -149,6 +150,26 @@ class BaseTestCase(testtools.TestCase):
         self.addCleanup(patcher.stop)
         return result
 
+    def delay_inaccurate_clock(self, duration=0.001):
+        """Add a small delay to compensate for inaccurate system clocks.
+
+        Some tests make assertions based on timestamps (e.g. comparing
+        'created_at' and 'updated_at' fields). In some cases, subsequent
+        time.time() calls may return identical values (python timestamps can
+        have a lower resolution on Windows compared to Linux - 1e-7 as
+        opposed to 1e-9).
+
+        A small delay (a few ms should be negligeable) can prevent such
+        issues. At the same time, it spares us from mocking the time
+        module, which might be undesired.
+        """
+
+        # For now, we'll do this only for Windows. If really needed,
+        # on Py3 we can get the clock resolution using time.get_clock_info,
+        # but at that point we may as well just sleep 1ms all the time.
+        if os.name == 'nt':
+            time.sleep(duration)
+
 
 class requires(object):
     """Decorator that initiates additional test setup/teardown."""