test(proxy): guard management_v1 against fastapi names removed in supported releases

tests/test_litellm/proxy/management_endpoints/management_v1/test_common.py

@@ -1,11 +1,18 @@
+import ast
+import importlib.util
+from pathlib import Path
+from types import ModuleType
 from typing import Annotated
 
+import fastapi.dependencies.utils as fastapi_dependency_utils
+import pytest
 from fastapi import Depends, FastAPI, Header, Query, Request
 from fastapi.testclient import TestClient
 
+import litellm.proxy.management_endpoints.management_v1.common as common_module
 from litellm.proxy.management_endpoints.management_v1.common import (
-    ManagementProblem,
     PROBLEM_CONTENT_TYPE,
+    ManagementProblem,
     _declared_query_params,
     problem_response,
     reject_unknown_query_params,
@@ -93,3 +100,57 @@ def test_declared_query_params_is_empty_when_the_route_has_no_dependant():
         }
     )
     assert _declared_query_params(request) == frozenset()
+
+
+# fastapi removed these in 0.140.7, which `pyproject.toml` still allows via
+# `fastapi>=0.136.3,<1.0`. Add a name here whenever a supported release drops one.
+FASTAPI_NAMES_REMOVED_IN_0_140_7 = frozenset({"get_flat_dependant"})
+
+MANAGEMENT_V1_PACKAGE = Path(str(common_module.__file__)).parent
+
+
+def _public_names(module: ModuleType) -> frozenset[str]:
+    return frozenset(name for name in vars(module) if not name.startswith("_"))
+
+
+def _fastapi_names_imported_by(source_file: Path) -> frozenset[str]:
+    tree = ast.parse(source_file.read_text())
+    return frozenset(
+        alias.name
+        for node in ast.walk(tree)
+        if isinstance(node, ast.ImportFrom) and (node.module or "").startswith("fastapi")
+        for alias in node.names
+    )
+
+
+@pytest.mark.parametrize(
+    "source_file", sorted(MANAGEMENT_V1_PACKAGE.glob("*.py")), ids=lambda path: path.name
+)
+def test_no_module_imports_a_fastapi_name_removed_in_a_supported_release(source_file: Path):
+    """`pyproject.toml` allows fastapi up to <1.0, but CI only ever resolves 0.136.3.
+
+    Every other test here passes just as well against a module importing a name
+    fastapi has since deleted, because the pinned fastapi still has it. On a user's
+    fastapi>=0.140.7 that import is an ImportError, and `proxy_server` imports this
+    package unguarded at module level, so it takes the whole proxy down rather than
+    just these routes. Globbing the package means a new module is covered on sight.
+    """
+    assert not _fastapi_names_imported_by(source_file) & FASTAPI_NAMES_REMOVED_IN_0_140_7
+
+
+def test_common_still_imports_when_fastapi_has_dropped_those_names(monkeypatch: pytest.MonkeyPatch):
+    """The static check above cannot prove the module actually loads; this does.
+
+    Behaviour cannot be asserted under the same simulation: on 0.136.3
+    `get_flat_params` calls `get_flat_dependant` internally, so it raises NameError
+    once the name is gone. Loading is the part this pins.
+    """
+    for name in FASTAPI_NAMES_REMOVED_IN_0_140_7:
+        monkeypatch.delattr(fastapi_dependency_utils, name, raising=False)
+    spec = importlib.util.spec_from_file_location(
+        "management_v1_common__simulated_fastapi", Path(str(common_module.__file__))
+    )
+    assert spec is not None and spec.loader is not None
+    reimported = importlib.util.module_from_spec(spec)
+    spec.loader.exec_module(reimported)
+    assert _public_names(reimported) == _public_names(common_module)