fix other cases

changedetectionio/model/Watch.py

@@ -271,14 +271,20 @@ class model(dict):
 
         """Unfortunately for now timestamp is stored as string key"""
         keys = list(self.history.keys())
+        if not keys:
+            return None
 
-        last_viewed = self.get('last_viewed')
+        last_viewed = int(self.get('last_viewed'))
         prev_k = keys[0]
         sorted_keys = sorted(keys, key=lambda x: int(x))
         sorted_keys.reverse()
 
+        # When the 'last viewed' timestamp is greater than the newest snapshot, return second last
+        if last_viewed > int(sorted_keys[0]):
+            return sorted_keys[1]
+
         for k in sorted_keys:
-            if int(k) < int(last_viewed):
+            if int(k) < last_viewed:
                 if prev_k == sorted_keys[0]:
                     # Return the second last one so we dont recommend the same version compares itself
                     return sorted_keys[1]

changedetectionio/tests/unit/test_watch_model.py

@@ -11,7 +11,7 @@ from changedetectionio.model import Watch
 # mostly
 class TestDiffBuilder(unittest.TestCase):
 
-    def test_watch_module(self):
+    def test_watch_get_suggested_from_diff_timestamp(self):
         import uuid as uuid_builder
         watch = Watch.model(datastore_path='/tmp', default={})
         watch.ensure_data_dir_exists()
@@ -33,6 +33,17 @@ class TestDiffBuilder(unittest.TestCase):
         p = watch.get_next_snapshot_key_to_last_viewed
         assert p == "115", "Correct 'second last' last-viewed timestamp was detected when using the last timestamp"
 
+        watch['last_viewed'] = 99
+        p = watch.get_next_snapshot_key_to_last_viewed
+        assert p == "100"
+
+        watch['last_viewed'] = 200
+        p = watch.get_next_snapshot_key_to_last_viewed
+        assert p == "115", "When the 'last viewed' timestamp is greater than the newest snapshot, return second last "
+
+        watch = Watch.model(datastore_path='/tmp', default={})
+        p = watch.get_next_snapshot_key_to_last_viewed
+        assert p == None, "None when no history available"
 
 if __name__ == '__main__':
     unittest.main()