Fix serve long running test (#8268)

python/ray/serve/config.py

@@ -11,6 +11,9 @@ def _callable_accepts_batch(func_or_class):
 class BackendConfig:
     def __init__(self, config_dict, accepts_batches=False):
         assert isinstance(config_dict, dict)
+        # Make a copy so that we don't modify the input dict.
+        config_dict = config_dict.copy()
+
         self.accepts_batches = accepts_batches
         self.num_replicas = config_dict.pop("num_replicas", 1)
         self.max_batch_size = config_dict.pop("max_batch_size", None)

python/ray/serve/tests/test_config.py

@@ -9,6 +9,11 @@ def test_backend_config_validation():
     with pytest.raises(ValueError, match="unknown_key"):
         BackendConfig({"unknown_key": -1})
 
+    # Test that the input dict isn't modified.
+    config = {"num_replicas": 2}
+    BackendConfig(config)
+    assert len(config) == 1 and config["num_replicas"] == 2
+
     # Test num_replicas validation.
     BackendConfig({"num_replicas": 1})
     with pytest.raises(TypeError):