diff --git a/tests/test_recall.py b/tests/test_recall.py
index 3e8b8fd..cd6ea2e 100644
--- a/tests/test_recall.py
+++ b/tests/test_recall.py
@@ -61,6 +61,27 @@ def test_RecallClass_score(self):
         with self.assertRaises(Exception):
             score = obj.score(real, pred)
 
+    def test_RecallClass_update_recall(self):
+        """Test of _update_recall function.
+        """
+
+        # test of the normal case
+        real = np.array([0, 1, 0, 0, 0])
+        pred = np.array([1, 1, 0, 0, 0])
+
+        obj = TimeSeriesRecall()
+        real_anomalies, predicted_anomalies = obj._prepare_data(real, pred)
+
+        score = obj._update_recall(real_anomalies, predicted_anomalies)
+        self.assertEqual(score, 1.0)
+
+        # test of the empty case
+        empty_real = np.array([])
+        empty_pred = np.array([])
+
+        score = obj._update_recall(empty_real, empty_pred)
+        self.assertEqual(score, 0.0)
+
     def test_recall_function(self):
         """Test of ts_recall function.
         """