Convert code-mode to the CodeMode plugin (#4002)

tests/server/plugins/test_code_mode_plugin.py

@@ -0,0 +1,105 @@
+"""Tests for the CodeMode plugin wrapper.
+
+Transform behavior (what `CodeModeTransform` does to the catalog, how
+discovery tools render, sandbox execution, etc.) is covered by
+`test_code_mode.py` and `test_code_mode_discovery.py`. This file only
+covers the plugin layer itself — config validation, meta derivation,
+dict-config coercion, and the deprecation shim at the old import path.
+"""
+
+from __future__ import annotations
+
+import warnings
+from typing import Any
+
+import pytest
+from pydantic import ValidationError
+
+from fastmcp import FastMCP
+from fastmcp.server.plugins.code_mode import CodeMode, CodeModeConfig
+
+
+class _NoopSandbox:
+    async def run(
+        self,
+        code: str,
+        *,
+        inputs: dict[str, Any] | None = None,
+        external_functions: dict[str, Any] | None = None,
+    ) -> Any:
+        return None
+
+
+class TestCodeModeConfig:
+    def test_config_generic_binding(self):
+        """`Plugin[CodeModeConfig]` binds CodeModeConfig as the validated config type."""
+        assert CodeMode._config_cls is CodeModeConfig
+
+    def test_dict_config_accepted(self):
+        """Dict config works for loading from JSON/YAML."""
+        plugin = CodeMode({"execute_tool_name": "go"})
+        assert plugin.config.execute_tool_name == "go"
+
+    def test_unknown_sandbox_rejected(self):
+        with pytest.raises((ValidationError, Exception), match="sandbox"):
+            CodeModeConfig(sandbox="docker")  # ty: ignore[invalid-argument-type]
+
+    def test_unknown_config_key_rejected(self):
+        with pytest.raises((ValidationError, Exception), match="forbid|extra"):
+            CodeModeConfig(not_a_real_option=True)  # ty: ignore[unknown-argument]
+
+    def test_default_meta(self):
+        """CodeMode uses Plugin's auto-derived meta: kebab-cased class
+        name, no independent version (bundled first-party plugin)."""
+        assert CodeMode.meta.name == "code-mode"
+        assert CodeMode.meta.version is None
+
+
+class TestDeprecationShim:
+    """The old `fastmcp.experimental.transforms.code_mode` path still works but warns."""
+
+    def test_old_package_import_emits_deprecation_warning(self):
+        import importlib
+        import sys
+
+        from fastmcp.exceptions import FastMCPDeprecationWarning
+
+        sys.modules.pop("fastmcp.experimental.transforms.code_mode", None)
+
+        with warnings.catch_warnings(record=True) as caught:
+            warnings.simplefilter("always")
+            importlib.import_module("fastmcp.experimental.transforms.code_mode")
+
+        fastmcp_deprecations = [
+            w for w in caught if issubclass(w.category, FastMCPDeprecationWarning)
+        ]
+        assert any(
+            "plugins.code_mode" in str(w.message) for w in fastmcp_deprecations
+        ), (
+            f"expected FastMCPDeprecationWarning pointing at plugins.code_mode, "
+            f"got {[(w.category.__name__, str(w.message)) for w in caught]}"
+        )
+
+    async def test_legacy_add_transform_pattern_still_works(self):
+        """End-to-end: old `add_transform(CodeMode(...))` code keeps
+        working. The point of the shim is that this doesn't break — the
+        identity-check test alone wouldn't catch a regression where
+        `CodeMode` at the old path drifted to the plugin class."""
+        from fastmcp.exceptions import FastMCPDeprecationWarning
+
+        with warnings.catch_warnings():
+            warnings.simplefilter("ignore", FastMCPDeprecationWarning)
+            from fastmcp.experimental.transforms.code_mode import (
+                CodeMode as OldCodeMode,
+            )
+
+        mcp = FastMCP("legacy")
+
+        @mcp.tool
+        def ping() -> str:
+            return "pong"
+
+        mcp.add_transform(OldCodeMode(sandbox_provider=_NoopSandbox()))
+
+        tools = await mcp.list_tools(run_middleware=False)
+        assert {t.name for t in tools} == {"search", "get_schema", "execute"}