Adds signal test, fix bug (#297)

* Adds signal test, fix bug

* Lint

* Fix

langgraph/src/pregel/index.ts

@@ -694,7 +694,7 @@ export class Pregel<
               proc.invoke(input, updatedConfig)
         );
 
-        await executeTasks(tasks, this.stepTimeout);
+        await executeTasks(tasks, this.stepTimeout, config.signal);
 
         // combine pending writes from all tasks
         const pendingWrites: Array<[keyof Cc, unknown]> = [];

langgraph/src/tests/prebuilt.test.ts

@@ -330,6 +330,42 @@ describe("createReactAgent", () => {
     ]);
   });
 
+  it("Should respect a passed signal", async () => {
+    const llm = new FakeToolCallingChatModel({
+      responses: [
+        new AIMessage({
+          content: "result1",
+          tool_calls: [
+            { name: "search_api", id: "tool_abcd123", args: { query: "foo" } },
+          ],
+        }),
+        new AIMessage("result2"),
+      ],
+      sleep: 500,
+    });
+
+    const agent = createReactAgent({
+      llm,
+      tools: [new SearchAPIWithArtifact()],
+      messageModifier: "You are a helpful assistant",
+    });
+
+    const controller = new AbortController();
+
+    setTimeout(() => controller.abort(), 100);
+
+    await expect(async () => {
+      await agent.invoke(
+        {
+          messages: [new HumanMessage("Hello Input!")],
+        },
+        {
+          signal: controller.signal,
+        }
+      );
+    }).rejects.toThrowError();
+  });
+
   it("Works with tools that return content_and_artifact response format", async () => {
     const llm = new FakeToolCallingChatModel({
       responses: [

langgraph/src/tests/utils.ts

@@ -1,3 +1,4 @@
+/* eslint-disable no-promise-executor-return */
 import assert from "node:assert";
 import { CallbackManagerForLLMRun } from "@langchain/core/callbacks/manager";
 import {
@@ -97,6 +98,9 @@ export class FakeToolCallingChatModel extends BaseChatModel {
     if (this.thrownErrorString) {
       throw new Error(this.thrownErrorString);
     }
+    if (this.sleep !== undefined) {
+      await new Promise((resolve) => setTimeout(resolve, this.sleep));
+    }
     const msg = this.responses?.[this.idx] ?? messages[this.idx];
     const generation: ChatResult = {
       generations: [