diff --git a/test/test_celery_worker_global.py b/test/test_celery_worker_global.py
index dd840d3f9e1ab189a974e48c0ab6d159fbbb3172..a67d07c47665ca9f97f0a51f4654103b34574fda 100644
--- a/test/test_celery_worker_global.py
+++ b/test/test_celery_worker_global.py
@@ -6,6 +6,8 @@ import contextlib
 import os
 
 from inventory_provider.tasks import worker
+from inventory_provider.tasks import common
+
 
 from inventory_provider.tasks.common import _get_redis
 
@@ -50,7 +52,26 @@ def test_update_locations(mocker, mocked_worker_module, mocked_redis):
 
 
 def test_InventoryTask_obj(data_config_filename):
-
     os.environ['INVENTORY_PROVIDER_CONFIG_FILENAME'] = data_config_filename
     task = worker.InventoryTask()
     assert task.config
+
+
+def test_next_redis(data_config, mocked_redis):
+    common.set_latch(data_config, 10, 20)
+    r = common.get_next_redis(data_config)
+    assert r
+
+    # there's only one ...
+    latch = common.get_latch(r)
+    assert latch['current'] == 10
+    assert latch['next'] == 20
+
+
+def test_next_redis_with_none(data_config, mocked_redis):
+    r = common._get_redis(data_config)
+    assert r
+
+    del r.db['db:latch']  # cf. conftest:MockedRedis
+    r = common.get_next_redis(data_config)
+    assert r