diff --git a/src/detector/detector.py b/src/detector/detector.py
index 687a9cd..3b7de11 100644
--- a/src/detector/detector.py
+++ b/src/detector/detector.py
@@ -8,6 +8,7 @@
 import numpy as np
 import math
 import requests
+from numpy import median
 
 sys.path.append(os.getcwd())
 from src.base.utils import setup_config
@@ -280,13 +281,12 @@ def detect(self) -> None:  # pragma: no cover
     def send_warning(self) -> None:
         logger.info("Store alert to file.")
         if len(self.warnings) > 0:
-            overall_score = 0
-            for warning in self.warnings:
-                overall_score += warning["probability"]
-            overall_score = overall_score / len(self.warnings)
+            overall_score = median(
+                [warning["probability"] for warning in self.warnings]
+            )
             alert = {"overall_score": overall_score, "result": self.warnings}
             logger.info(f"Add alert: {alert}")
-            with open(os.path.join(tempfile.gettempdir(), "warnings.json"), "a") as f:
+            with open(os.path.join(tempfile.gettempdir(), "warnings.json"), "a+") as f:
                 json.dump(alert, f)
                 f.write("\n")
         else:
diff --git a/tests/test_detector.py b/tests/test_detector.py
index f9dbe91..b3fb72b 100644
--- a/tests/test_detector.py
+++ b/tests/test_detector.py
@@ -1,6 +1,8 @@
+import os
+import tempfile
 import unittest
 from datetime import datetime, timedelta
-from unittest.mock import MagicMock, patch
+from unittest.mock import MagicMock, patch, mock_open
 
 from requests import HTTPError
 
@@ -217,6 +219,98 @@ def test_get_data_while_busy(self, mock_kafka_consume_handler, mock_logger):
         self.assertEqual([{"test": "test_message_2"}], sut.messages)
 
 
+class TestSendWarning(unittest.TestCase):
+    def setUp(self):
+        patcher = patch("src.detector.detector.logger")
+        self.mock_logger = patcher.start()
+        self.addCleanup(patcher.stop)
+
+    @patch(
+        "src.detector.detector.CHECKSUM",
+        "ba1f718179191348fe2abd51644d76191d42a5d967c6844feb3371b6f798bf06",
+    )
+    @patch("src.detector.detector.MODEL", "rf")
+    @patch(
+        "src.detector.detector.MODEL_BASE_URL",
+        "https://heibox.uni-heidelberg.de/d/0d5cbcbe16cd46a58021/",
+    )
+    @patch("src.detector.detector.KafkaConsumeHandler")
+    def test_save_warning(self, mock_kafka_consume_handler):
+        mock_kafka_consume_handler_instance = MagicMock()
+        mock_kafka_consume_handler.return_value = mock_kafka_consume_handler_instance
+
+        sut = Detector()
+        sut.warnings = [
+            {
+                "request": "google.de",
+                "probability": 0.8765,
+                "model": "rf",
+                "sha256": "ba1f718179191348fe2abd51644d76191d42a5d967c6844feb3371b6f798bf06",
+            },
+            {
+                "request": "request.de",
+                "probability": 0.12388,
+                "model": "rf",
+                "sha256": "ba1f718179191348fe2abd51644d76191d42a5d967c6844feb3371b6f798bf06",
+            },
+        ]
+        open_mock = mock_open()
+        with patch("src.detector.detector.open", open_mock, create=True):
+            sut.send_warning()
+
+        open_mock.assert_called_with(
+            os.path.join(tempfile.gettempdir(), "warnings.json"), "a+"
+        )
+
+    @patch(
+        "src.detector.detector.CHECKSUM",
+        "ba1f718179191348fe2abd51644d76191d42a5d967c6844feb3371b6f798bf06",
+    )
+    @patch("src.detector.detector.MODEL", "rf")
+    @patch(
+        "src.detector.detector.MODEL_BASE_URL",
+        "https://heibox.uni-heidelberg.de/d/0d5cbcbe16cd46a58021/",
+    )
+    @patch("src.detector.detector.KafkaConsumeHandler")
+    def test_save_empty_warning(self, mock_kafka_consume_handler):
+        mock_kafka_consume_handler_instance = MagicMock()
+        mock_kafka_consume_handler.return_value = mock_kafka_consume_handler_instance
+
+        sut = Detector()
+        sut.warnings = []
+        open_mock = mock_open()
+        with patch("src.detector.detector.open", open_mock, create=True):
+            sut.send_warning()
+
+        open_mock.assert_not_called()
+
+    @patch(
+        "src.detector.detector.CHECKSUM",
+        "ba1f718179191348fe2abd51644d76191d42a5d967c6844feb3371b6f798bf06",
+    )
+    @patch("src.detector.detector.MODEL", "rf")
+    @patch(
+        "src.detector.detector.MODEL_BASE_URL",
+        "https://heibox.uni-heidelberg.de/d/0d5cbcbe16cd46a58021/",
+    )
+    @patch("src.detector.detector.KafkaConsumeHandler")
+    def test_save_warning_error(self, mock_kafka_consume_handler):
+        mock_kafka_consume_handler_instance = MagicMock()
+        mock_kafka_consume_handler.return_value = mock_kafka_consume_handler_instance
+
+        sut = Detector()
+        sut.warnings = [
+            {
+                "request": "request.de",
+                "probability": "INVALID",
+                "model": "rf",
+                "sha256": "ba1f718179191348fe2abd51644d76191d42a5d967c6844feb3371b6f798bf06",
+            }
+        ]
+        with self.assertRaises(Exception):
+            sut.send_warning()
+
+
 class TestClearData(unittest.TestCase):
     def setUp(self):
         patcher = patch("src.detector.detector.logger")