【Hackathon 9th No.77】supplementary unit test for get_filtered_metrics (#3578)

* 功能模块 fastdeploy/metrics/metrics/get_filtered_metrics 单测补充

* fix pre-commit

---------

Co-authored-by: Tao Luo <luotao02@baidu.com>

tests/metrics/test_metrics.py

@@ -0,0 +1,72 @@
+"""
+# Copyright (c) 2025  PaddlePaddle Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""
+
+import unittest
+from unittest.mock import patch
+
+from prometheus_client import Gauge
+
+from fastdeploy.metrics.metrics import get_filtered_metrics
+
+
+class TestGetFilteredMetrics(unittest.TestCase):
+    def test_filtered_and_custom_metrics(self):
+        """
+        Test get_filtered_metrics function:
+        1. Exclude specific metrics from base_registry
+        2. Keep other metrics in base_registry
+        3. Ensure metrics registered by extra_register_func are effective
+        """
+
+        exclude_names = {"metric_to_exclude"}
+
+        # Simulated metrics in base_registry (Gauge instances)
+        g_keep = Gauge("metric_to_keep", "Kept metric")
+        g_keep.set(1.23)
+
+        g_exclude = Gauge("metric_to_exclude", "Excluded metric")
+        g_exclude.set(99)
+
+        # Fake MultiProcessCollector: register our simulated metrics
+        def fake_multiprocess_collector(registry):
+            registry.register(g_keep)
+            registry.register(g_exclude)
+
+        # Custom metric via extra_register_func
+        def extra_func(registry):
+            g_custom = Gauge("custom_metric_total", "Custom metric")
+            g_custom.set(42)
+            registry.register(g_custom)
+
+        with patch(
+            "fastdeploy.metrics.metrics.multiprocess.MultiProcessCollector", side_effect=fake_multiprocess_collector
+        ):
+            result = get_filtered_metrics(exclude_names=exclude_names, extra_register_func=extra_func)
+
+        print("==== result ====\n", result)
+
+        # 1. Excluded metric should not appear
+        self.assertNotIn("metric_to_exclude", result)
+
+        # 2. Kept metric should appear
+        self.assertIn("metric_to_keep", result)
+
+        # 3. Custom metric should appear
+        self.assertIn("custom_metric_total", result)
+
+
+if __name__ == "__main__":
+    unittest.main()