Add mcp.types as a permanent alias for mcp_types (#3190)

tests/test_types.py

@@ -1,5 +1,12 @@
+import subprocess
+import sys
+from types import ModuleType
 from typing import Any
 
+import mcp_types
+import mcp_types.jsonrpc
+import mcp_types.methods
+import mcp_types.version
 import pytest
 from inline_snapshot import snapshot
 from mcp_types import (
@@ -38,6 +45,12 @@ from mcp_types import (
 )
 from pydantic import ValidationError
 
+import mcp
+import mcp.types
+import mcp.types.jsonrpc
+import mcp.types.methods
+import mcp.types.version
+
 
 @pytest.mark.anyio
 async def test_jsonrpc_request():
@@ -445,3 +458,48 @@ def test_input_required_result_requires_at_least_one_of_input_requests_or_reques
     with pytest.raises(ValidationError):
         InputRequiredResult(input_requests={})
     assert InputRequiredResult(request_state="s").input_requests is None
+
+
+def _assert_mirrors(mirror: ModuleType, source: ModuleType) -> None:
+    # The mirror shares the source's `__all__` list object by construction (`from source import
+    # __all__`), so the meaningful proof is that every exported name is the identical object.
+    assert all(getattr(mirror, name) is getattr(source, name) for name in source.__all__)
+
+
+def test_mcp_types_namespace_mirrors_mcp_types_exactly():
+    """SDK-defined: `mcp.types` is a permanent alias whose every name is the `mcp_types` object."""
+    _assert_mirrors(mcp.types, mcp_types)
+
+
+@pytest.mark.parametrize(
+    ("mirror", "source"),
+    [
+        (mcp.types.jsonrpc, mcp_types.jsonrpc),
+        (mcp.types.methods, mcp_types.methods),
+        (mcp.types.version, mcp_types.version),
+    ],
+    ids=["jsonrpc", "methods", "version"],
+)
+def test_mcp_types_submodules_mirror_mcp_types_submodules_exactly(mirror: ModuleType, source: ModuleType):
+    """SDK-defined: every supported `mcp_types` submodule has an `mcp.types` mirror, name for name."""
+    _assert_mirrors(mirror, source)
+
+
+def test_bare_import_mcp_binds_the_types_submodule():
+    """SDK-defined: `import mcp` alone binds `mcp.types`, so v1's `mcp.types.Tool` idiom works.
+
+    A fresh interpreter is required to observe `import mcp` in isolation: this test process
+    has already imported `mcp.types`, and reloading `mcp` here would rebind classes that other
+    tests hold references to.
+    """
+    # A regression hangs forever, so the bound only has to beat never (matches the suite's
+    # other subprocess.run calls).
+    result = subprocess.run(
+        [sys.executable, "-c", "import mcp; print(mcp.types.Tool.__name__)"],
+        capture_output=True,
+        text=True,
+        check=False,
+        timeout=20,
+    )
+    assert result.returncode == 0, result.stderr
+    assert result.stdout == snapshot("Tool\n")