add test

.github/workflows/_test_langgraph.yml

@@ -56,3 +56,46 @@ jobs:
           # grep will exit non-zero if the target message isn't found,
           # and `set -e` above will cause the step to fail.
           echo "$STATUS" | grep 'nothing to commit, working tree clean'
+
+  build-strict-msgpack:
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        working-directory: libs/langgraph
+    name: "test strict msgpack #3.12"
+    steps:
+      - uses: actions/checkout@v6
+      - name: Set up Python 3.12
+        uses: astral-sh/setup-uv@v7
+        with:
+          python-version: "3.12"
+          enable-cache: true
+          cache-suffix: "test-langgraph-strict-msgpack"
+      - name: Login to Docker Hub
+        uses: docker/login-action@v3
+        if: ${{ !github.event.pull_request.head.repo.fork }}
+        with:
+          username: ${{ secrets.DOCKERHUB_USERNAME }}
+          password: ${{ secrets.DOCKERHUB_RO_TOKEN }}
+
+      - name: Install dependencies
+        shell: bash
+        run: uv sync --frozen --group test --no-dev
+
+      - name: Run tests (strict msgpack)
+        shell: bash
+        env:
+          LANGGRAPH_STRICT_MSGPACK: "1"
+        run: make test_parallel
+
+      - name: Ensure the tests did not create any additional files
+        shell: bash
+        run: |
+          set -eu
+
+          STATUS="$(git status)"
+          echo "$STATUS"
+
+          # grep will exit non-zero if the target message isn't found,
+          # and `set -e` above will cause the step to fail.
+          echo "$STATUS" | grep 'nothing to commit, working tree clean'

libs/langgraph/tests/conftest_checkpointer.py

@@ -1,3 +1,4 @@
+import os
 from contextlib import asynccontextmanager, contextmanager
 from uuid import uuid4
 
@@ -5,6 +6,7 @@ import pytest
 from langgraph.checkpoint.postgres import PostgresSaver
 from langgraph.checkpoint.postgres.aio import AsyncPostgresSaver
 from langgraph.checkpoint.serde.encrypted import EncryptedSerializer
+from langgraph.checkpoint.serde.jsonplus import JsonPlusSerializer
 from langgraph.checkpoint.sqlite import SqliteSaver
 from langgraph.checkpoint.sqlite.aio import AsyncSqliteSaver
 from psycopg import AsyncConnection, Connection
@@ -18,30 +20,60 @@ from tests.memory_assert import (  # noqa: E402
 )
 
 DEFAULT_POSTGRES_URI = "postgres://postgres:postgres@localhost:5442/"
+STRICT_MSGPACK = os.getenv("LANGGRAPH_STRICT_MSGPACK", "false").lower() in (
+    "1",
+    "true",
+    "yes",
+)
+
+
+def _strict_msgpack_serde() -> JsonPlusSerializer:
+    return JsonPlusSerializer(allowed_msgpack_modules=None)
+
+
+def _apply_strict_msgpack(checkpointer) -> None:
+    if not STRICT_MSGPACK:
+        return
+    serde = _strict_msgpack_serde()
+    if hasattr(checkpointer, "serde"):
+        checkpointer.serde = serde
+    if hasattr(checkpointer, "saver") and hasattr(checkpointer.saver, "serde"):
+        checkpointer.saver.serde = serde
 
 
 @contextmanager
 def _checkpointer_memory():
-    yield MemorySaverAssertImmutable()
+    if STRICT_MSGPACK:
+        yield MemorySaverAssertImmutable(serde=_strict_msgpack_serde())
+    else:
+        yield MemorySaverAssertImmutable()
 
 
 @contextmanager
 def _checkpointer_memory_migrate_sends():
-    yield MemorySaverNeedsPendingSendsMigration()
+    checkpointer = MemorySaverNeedsPendingSendsMigration()
+    _apply_strict_msgpack(checkpointer)
+    yield checkpointer
 
 
 @contextmanager
 def _checkpointer_sqlite():
     with SqliteSaver.from_conn_string(":memory:") as checkpointer:
+        _apply_strict_msgpack(checkpointer)
         yield checkpointer
 
 
 @contextmanager
 def _checkpointer_sqlite_aes():
     with SqliteSaver.from_conn_string(":memory:") as checkpointer:
-        checkpointer.serde = EncryptedSerializer.from_pycryptodome_aes(
-            key=b"1234567890123456"
-        )
+        if STRICT_MSGPACK:
+            checkpointer.serde = EncryptedSerializer.from_pycryptodome_aes(
+                serde=_strict_msgpack_serde(), key=b"1234567890123456"
+            )
+        else:
+            checkpointer.serde = EncryptedSerializer.from_pycryptodome_aes(
+                key=b"1234567890123456"
+            )
         yield checkpointer
 
 
@@ -57,6 +89,7 @@ def _checkpointer_postgres():
             DEFAULT_POSTGRES_URI + database
         ) as checkpointer:
             checkpointer.setup()
+            _apply_strict_msgpack(checkpointer)
             yield checkpointer
     finally:
         # drop unique db
@@ -79,6 +112,7 @@ def _checkpointer_postgres_pipe():
             # setup can't run inside pipeline because of implicit transaction
             with checkpointer.conn.pipeline() as pipe:
                 checkpointer.pipe = pipe
+                _apply_strict_msgpack(checkpointer)
                 yield checkpointer
     finally:
         # drop unique db
@@ -99,6 +133,7 @@ def _checkpointer_postgres_pool():
         ) as pool:
             checkpointer = PostgresSaver(pool)
             checkpointer.setup()
+            _apply_strict_msgpack(checkpointer)
             yield checkpointer
     finally:
         # drop unique db
@@ -109,6 +144,7 @@ def _checkpointer_postgres_pool():
 @asynccontextmanager
 async def _checkpointer_sqlite_aio():
     async with AsyncSqliteSaver.from_conn_string(":memory:") as checkpointer:
+        _apply_strict_msgpack(checkpointer)
         yield checkpointer
 
 
@@ -126,6 +162,7 @@ async def _checkpointer_postgres_aio():
             DEFAULT_POSTGRES_URI + database
         ) as checkpointer:
             await checkpointer.setup()
+            _apply_strict_msgpack(checkpointer)
             yield checkpointer
     finally:
         # drop unique db
@@ -152,6 +189,7 @@ async def _checkpointer_postgres_aio_pipe():
             # setup can't run inside pipeline because of implicit transaction
             async with checkpointer.conn.pipeline() as pipe:
                 checkpointer.pipe = pipe
+                _apply_strict_msgpack(checkpointer)
                 yield checkpointer
     finally:
         # drop unique db
@@ -176,6 +214,7 @@ async def _checkpointer_postgres_aio_pool():
         ) as pool:
             checkpointer = AsyncPostgresSaver(pool)
             await checkpointer.setup()
+            _apply_strict_msgpack(checkpointer)
             yield checkpointer
     finally:
         # drop unique db