Start dev server externally (#4604)

Signed-off-by: William Fu-Hinthorn <13333726+hinthornw@users.noreply.github.com>

libs/langgraph/.gitignore

@@ -1 +1,2 @@
 .langgraph_api/
+.devserver.pid

libs/langgraph/Makefile

@@ -41,20 +41,36 @@ stop-postgres:
 	docker compose -f tests/compose-postgres.yml down -v
 
 start-dev-server:
-	poetry run langgraph dev --config integration_tests/example_app/langgraph.json --no-browser
+	poetry run langgraph dev --config tests/example_app/langgraph.json --no-browser &
+	@echo "Dev server started."
+	@echo "Dev server PID: $$!" > .devserver.pid
+
+stop-dev-server:
+	@if [ -f .devserver.pid ]; then \
+		kill `cat .devserver.pid` && rm .devserver.pid; \
+		 echo "Dev server stopped."; \
+	else \
+		echo "No dev server PID file found."; \
+	fi
 
 TEST ?= .
 
 test:
-	make start-postgres && poetry run pytest $(TEST); \
+	make start-postgres &&\
+	make start-dev-server &&\
+	poetry run pytest $(TEST); \
 	EXIT_CODE=$$?; \
 	make stop-postgres; \
+	make stop-dev-server; \
 	exit $$EXIT_CODE
 
 test_parallel:
-	make start-postgres && poetry run pytest -n auto --dist worksteal $(TEST); \
+	make start-postgres &&\
+	make start-dev-server &&\
+	poetry run pytest -n auto --dist worksteal $(TEST); \
 	EXIT_CODE=$$?; \
 	make stop-postgres; \
+	make stop-dev-server; \
 	exit $$EXIT_CODE
 
 integration_tests:
@@ -68,9 +84,12 @@ MAXFAIL_ARGS := $(if $(MAXFAIL),--maxfail $(MAXFAIL),)
 XDIST_ARGS := $(if $(WORKERS),-x $(XDIST_ARGS),)
 
 test_watch:
-	make start-postgres && poetry run ptw . -- --ff -vv $(XDIST_ARGS) $(MAXFAIL_ARGS) $(TEST); \
+	make start-postgres &&\
+	make start-dev-server &&\
+	poetry run ptw . -- --ff -vv $(XDIST_ARGS) $(MAXFAIL_ARGS) $(TEST); \
 	EXIT_CODE=$$?; \
 	make stop-postgres; \
+	make stop-dev-server; \
 	exit $$EXIT_CODE
 
 test_watch_all:

libs/langgraph/tests/conftest.py

@@ -1,13 +1,10 @@
-import subprocess
 import sys
-import time
 from collections.abc import AsyncIterator
 from contextlib import asynccontextmanager
 from typing import Optional
 from uuid import UUID, uuid4
 
 import pytest
-import requests
 from langchain_core import __version__ as core_version
 from packaging import version
 from psycopg import AsyncConnection, Connection
@@ -444,55 +441,6 @@ async def awith_store(store_name: Optional[str]) -> AsyncIterator[BaseStore]:
         raise NotImplementedError(f"Unknown store {store_name}")
 
 
-@pytest.fixture(scope="session", autouse=True)
-def dev_server():
-    # Command to start the dev server
-    if sys.version_info < (3, 11):
-        # We'll skip these tests
-        yield
-        return
-    cmd = [
-        "poetry",
-        "run",
-        "langgraph",
-        "dev",
-        "--config",
-        "tests/example_app/langgraph.json",
-        "--no-browser",
-        "--port",
-        "2024",
-    ]
-    server = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
-    url = "http://localhost:2024/ok"
-    timeout = 30
-    start = time.time()
-    while True:
-        if server.poll() is not None:
-            out, err = server.communicate()
-            raise RuntimeError(
-                f"Dev server exited early.\nstdout: {out.decode()}\nstderr: {err.decode()}"
-            )
-        try:
-            resp = requests.get(url)
-            if resp.status_code == 200:
-                break
-        except Exception:
-            pass
-        if time.time() - start > timeout:
-            server.terminate()
-            out, err = server.communicate()
-            raise TimeoutError(
-                f"Timed out waiting for dev server to start.\nstdout: {out.decode()}\nstderr: {err.decode()}"
-            )
-        time.sleep(0.25)
-    yield
-    server.terminate()
-    try:
-        server.wait(timeout=10)
-    except subprocess.TimeoutExpired:
-        server.kill()
-
-
 SHALLOW_CHECKPOINTERS_SYNC = ["postgres_shallow"]
 REGULAR_CHECKPOINTERS_SYNC = [
     "memory",