core[tests]: Better tests for runnable history (#3537)

* core[tests]: Better tests for runnable history

* cr

langchain-core/src/runnables/history.ts

@@ -27,13 +27,14 @@ type GetSessionHistoryCallable = (
 export interface RunnableWithMessageHistoryInputs<RunInput, RunOutput>
   extends Omit<
     RunnableBindingArgs<RunInput, RunOutput, BaseCallbackConfig>,
-    "bound"
+    "bound" | "config"
   > {
   runnable: Runnable<RunInput, RunOutput>;
   getMessageHistory: GetSessionHistoryCallable;
   inputMessagesKey?: string;
   outputMessagesKey?: string;
   historyMessagesKey?: string;
+  config?: RunnableConfig;
 }
 
 export class RunnableWithMessageHistory<
@@ -70,8 +71,11 @@ export class RunnableWithMessageHistory<
       )
       .withConfig({ runName: "RunnableWithMessageHistory" });
 
+    const config = fields.config ?? {};
+
     super({
       ...fields,
+      config,
       bound,
     });
     this.runnable = fields.runnable;

langchain-core/src/runnables/tests/runnable_history.test.ts

@@ -8,8 +8,10 @@ import {
 } from "../../chat_history.js";
 import {
   FakeChatMessageHistory,
+  FakeLLM,
   FakeListChatMessageHistory,
 } from "../../utils/testing/index.js";
+import { ChatPromptTemplate, MessagesPlaceholder } from "../../prompts/chat.js";
 
 // For `BaseChatMessageHistory`
 async function getGetSessionHistory(): Promise<
@@ -90,3 +92,31 @@ test("Runnable with message history work with chat list memory", async () => {
   output = await withHistory.invoke([new HumanMessage("good bye")], config);
   expect(output).toBe("you said: hello\ngood bye");
 });
+
+test("Runnable with message history and RunnableSequence", async () => {
+  const prompt = ChatPromptTemplate.fromMessages([
+    ["ai", "You are a helpful assistant"],
+    new MessagesPlaceholder("history"),
+    ["human", "{input}"],
+  ]);
+  const model = new FakeLLM({});
+  const chain = prompt.pipe(model);
+
+  const getListMessageHistory = await getListSessionHistory();
+  const withHistory = new RunnableWithMessageHistory({
+    runnable: chain,
+    config: {},
+    getMessageHistory: getListMessageHistory,
+    inputMessagesKey: "input",
+    historyMessagesKey: "history",
+  });
+  const config: RunnableConfig = { configurable: { sessionId: "1" } };
+  let output = await withHistory.invoke({ input: "hello" }, config);
+  expect(output).toBe("AI: You are a helpful assistant\nHuman: hello");
+  output = await withHistory.invoke({ input: "good bye" }, config);
+  expect(output).toBe(`AI: You are a helpful assistant
+Human: hello
+AI: AI: You are a helpful assistant
+Human: hello
+Human: good bye`);
+});