Compares timestamps with assertAlmostEqual (#1262)

* Compares timestamps with assertAlmostEqual

The test_get_backup test has been flaking due to
doing equality comparisons on timestamps before
and after database transactions. These comparisons
have been changed to ensuring the timestamps are
within a certain threshold (currently 5 seconds).

Fixes #1255

Signed-off-by: Colin Schoen <[email protected]>

* Add additional datetime string formatting constants

Signed-off-by: Colin Schoen <[email protected]>

* Use new response_json local variable.

Signed-off-by: Colin Schoen <[email protected]>

* Fix typo in spelling datetime incorrectly

Signed-off-by: Colin Schoen <[email protected]>

* Use dateutil parser instead of datetime library

Signed-off-by: Colin Schoen <[email protected]>

Author: colinschoen

tests/test_api.py

@@ -1,7 +1,10 @@
 import datetime as dt
+import dateutil.parser
 import json
 import random
 
+from server import constants
+
 from server.models import (db, Assignment, Backup, Course, User,
                            Version, Group)
 from server.utils import encode_id
@@ -128,11 +131,24 @@ def test_get_backup(self):
             "email": backup.submitter.email,
             "id": encode_id(backup.submitter_id),
         }
-        assert response.json['data'] == {
+        response_json = response.json['data']
+        time_threshold = dt.timedelta(seconds=5)
+        self.assertAlmostEqual(dateutil.parser.parse(response_json['created']),
+                               backup.created,
+                               delta=time_threshold)
+        self.assertAlmostEqual(dateutil.parser.parse(response_json['submission_time']),
+                               submission_time,
+                               delta=time_threshold)
+        self.assertAlmostEqual(dateutil.parser.parse(response_json['messages'][0]['created']),
+                               backup.created,
+                               delta=time_threshold)
+        # Unset timestamps already tested.
+        del response_json['created']
+        del response_json['submission_time']
+        del response_json['messages'][0]['created']
+        assert response_json == {
             "submitter": user_json,
             "submit": backup.submit,
-            "created": backup.created.isoformat(),
-            "submission_time": submission_time.isoformat(),
             "group": [user_json],
             "is_late": backup.is_late,
             "external_files": [],
@@ -151,7 +167,6 @@ def test_get_backup(self):
                 {
                     "kind": "file_contents",
                     "contents": backup.files(),
-                    "created": backup.created.isoformat(),
                 },
             ],
         }