fix: server rooth path (#19790)

tests/proxy_unit_tests/test_server_root_path.py

@@ -0,0 +1,64 @@
+import os
+from unittest import mock
+from litellm.proxy import utils
+
+
+# Test the utility function logic
+def test_get_server_root_path_unset():
+    """
+    Test that get_server_root_path returns empty string when SERVER_ROOT_PATH is unset
+    """
+    with mock.patch.dict(os.environ, {}, clear=True):
+        # We need to make sure SERVER_ROOT_PATH is not in env
+        if "SERVER_ROOT_PATH" in os.environ:
+            del os.environ["SERVER_ROOT_PATH"]
+
+        root_path = utils.get_server_root_path()
+        assert (
+            root_path == ""
+        ), "Should return empty string when unset to allow X-Forwarded-Prefix"
+
+
+def test_get_server_root_path_set():
+    """
+    Test that get_server_root_path returns the value when SERVER_ROOT_PATH is set
+    """
+    with mock.patch.dict(os.environ, {"SERVER_ROOT_PATH": "/my-path"}, clear=True):
+        root_path = utils.get_server_root_path()
+        assert root_path == "/my-path", "Should return the set value"
+
+
+def test_get_server_root_path_empty_string():
+    """
+    Test that get_server_root_path returns empty string when SERVER_ROOT_PATH is explicitly empty
+    """
+    with mock.patch.dict(os.environ, {"SERVER_ROOT_PATH": ""}, clear=True):
+        root_path = utils.get_server_root_path()
+        assert (
+            root_path == ""
+        ), "Should return empty string when explicitly set to empty"
+
+
+# Integration test simulation for FastAPI app initialization
+def test_fastapi_app_initialization_mock():
+    """
+    Simulate how proxy_server.py initializes FastAPI app with the root_path.
+    We don't import proxy_server because it has global side effects/singletons.
+    Instead we verify the logic flow.
+    """
+    from fastapi import FastAPI
+
+    # CASE 1: Proxy Mode (Unset)
+    with mock.patch.dict(os.environ, {}, clear=True):
+        if "SERVER_ROOT_PATH" in os.environ:
+            del os.environ["SERVER_ROOT_PATH"]
+
+        server_root_path = utils.get_server_root_path()
+        app = FastAPI(root_path=server_root_path)
+        assert app.root_path == ""
+
+    # CASE 2: Direct Mode (Set)
+    with mock.patch.dict(os.environ, {"SERVER_ROOT_PATH": "/custom-root"}, clear=True):
+        server_root_path = utils.get_server_root_path()
+        app = FastAPI(root_path=server_root_path)
+        assert app.root_path == "/custom-root"