模拟 LLM
LangChain 提供一个模拟 LLM 聊天模型用于测试目的。这允许你模拟对 LLM 的调用，并模拟 LLM 以特定方式响应时会发生的情况。
用法
import { FakeListChatModel } from "@langchain/core/utils/testing";
import { HumanMessage } from "@langchain/core/messages";
import { StringOutputParser } from "@langchain/core/output_parsers";
/**
* The FakeListChatModel can be used to simulate ordered predefined responses.
*/
const chat = new FakeListChatModel({
responses: ["I'll callback later.", "You 'console' them!"],
});
const firstMessage = new HumanMessage("You want to hear a JavasSript joke?");
const secondMessage = new HumanMessage(
"How do you cheer up a JavaScript developer?"
);
const firstResponse = await chat.invoke([firstMessage]);
const secondResponse = await chat.invoke([secondMessage]);
console.log({ firstResponse });
console.log({ secondResponse });
/**
* The FakeListChatModel can also be used to simulate streamed responses.
*/
const stream = await chat
.pipe(new StringOutputParser())
.stream(`You want to hear a JavasSript joke?`);
const chunks = [];
for await (const chunk of stream) {
chunks.push(chunk);
}
console.log(chunks.join(""));
/**
* The FakeListChatModel can also be used to simulate delays in either either synchronous or streamed responses.
*/
const slowChat = new FakeListChatModel({
responses: ["Because Oct 31 equals Dec 25", "You 'console' them!"],
sleep: 1000,
});
const thirdMessage = new HumanMessage(
"Why do programmers always mix up Halloween and Christmas?"
);
const slowResponse = await slowChat.invoke([thirdMessage]);
console.log({ slowResponse });
const slowStream = await slowChat
.pipe(new StringOutputParser())
.stream("How do you cheer up a JavaScript developer?");
const slowChunks = [];
for await (const chunk of slowStream) {
slowChunks.push(chunk);
}
console.log(slowChunks.join(""));
API 参考
- FakeListChatModel 来自
@langchain/core/utils/testing - HumanMessage 来自
@langchain/core/messages - StringOutputParser 来自
@langchain/core/output_parsers