@@ -37,3 +37,64 @@ def test_plotusers_loads_local_plotly(client):
     with patch('google.cloud.ndb.Key', return_value=mock_key_instance):
         response = client.get('/plotusers')
     assert b'plotlyVP7.min.js' in response.data
+
+
+def test_update_user_count_no_cron_header(client):
+    """Returns 403 when X-Appengine-Cron header is absent."""
+    response = client.get('/admin/update-user-count')
+    assert response.status_code == 403
+
+
+def test_update_user_count_appends_new_point(client):
+    """Appends a new data point to existing history and returns 200."""
+    existing = {
+        'updated': '2026-04-01',
+        'points': [{'month': '2012-09', 'count': 320}],
+    }
+
+    stat_mock = MagicMock()
+    stat_mock.count = 314925
+
+    setting_mock = MagicMock()
+    setting_mock.value = json.dumps(existing)
+
+    def key_factory(*args, **kwargs):
+        m = MagicMock()
+        if args and args[0] == '__Stat_Kind__':
+            m.get.return_value = stat_mock
+        else:
+            m.get.return_value = setting_mock
+        return m
+
+    with patch('google.cloud.ndb.Key', side_effect=key_factory):
+        response = client.get('/admin/update-user-count',
+                              headers={'X-Appengine-Cron': 'true'})
+
+    assert response.status_code == 200
+    updated_history = json.loads(setting_mock.value)
+    assert len(updated_history['points']) == 2
+    assert updated_history['points'][-1]['count'] == 314925
+    setting_mock.put.assert_called_once()
+
+
+def test_update_user_count_creates_setting_when_missing(client):
+    """Creates a new Setting entity when none exists."""
+    stat_mock = MagicMock()
+    stat_mock.count = 100
+
+    def key_factory(*args, **kwargs):
+        m = MagicMock()
+        if args and args[0] == '__Stat_Kind__':
+            m.get.return_value = stat_mock
+        else:
+            m.get.return_value = None
+        return m
+
+    with patch('google.cloud.ndb.Key', side_effect=key_factory), \
+         patch('ide.routes.Setting') as mock_setting_class:
+        response = client.get('/admin/update-user-count',
+                              headers={'X-Appengine-Cron': 'true'})
+
+    assert response.status_code == 200
+    mock_setting_class.assert_called_once_with(id='user_count_history')
+    mock_setting_class.return_value.put.assert_called_once()