OpenAI API Mock

This is a Node.js module for mocking OpenAI API responses in a development environment.

It's useful for testing and development purposes when you don't want to make actual API calls.

The module supports the following OpenAI API endpoints:

chat completions
chat completions with streaming
chat completions with functions
image generations

This module is powering the sandbox mode for Aipify.

Installation

You can install this module using npm as a dev dependency :

npm install -D openai-api-mock

Usage

The module supports both ESM and CommonJS imports:

// ESM
import { mockOpenAIResponse } from 'openai-api-mock';

// CommonJS
const { mockOpenAIResponse } = require('openai-api-mock');

Then, call the mockOpenAIResponse function to set up the mock response:

// Basic usage
mockOpenAIResponse();

// Force mocking regardless of environment
mockOpenAIResponse(true);

// With configuration options
mockOpenAIResponse(false, {
    includeErrors: true,    // Simulate random API errors
    latency: 1000,         // Add 1 second delay to responses
    logRequests: true      // Log incoming requests to console
});

The function accepts two parameters:

force (boolean): Determines whether the mock response should be used regardless of the environment. If false or not provided, mocking only occurs in development environment.
options (object): Additional configuration options
- includeErrors (boolean): When true, randomly simulates API errors
- latency (number): Adds artificial delay to responses in milliseconds
- logRequests (boolean): Logs incoming requests to console for debugging

The function returns an object with control methods:

const mock = mockOpenAIResponse();

// Check if mocking is active
console.log(mock.isActive);

// Stop all mocks
mock.stopMocking();

// Add custom endpoint mock (uses api.openai.com as base url)
mock.addCustomEndpoint('POST', '/v1/custom', (uri, body) => {
    return [200, { custom: 'response' }];
});

Example responses

// Call the mockOpenAIResponse function once to set up the mock
mockOpenAIResponse() 

// Now, when you call the OpenAI API, it will return a mock response
const response = await openai.chat.completions.create({
                model: "gpt-3.5",
                messages: [
                    { role: 'system', content: "You're an expert chef" },
                    { role: 'user', content: "Suggest at least 5 recipes" },
                ]
});

In this example, the response constant will contain mock data, simulating a response from the OpenAI API:

{
    choices: [
        {
          finish_reason: 'stop',
          index: 0,
          message: [Object],
          logprobs: null
        }
      ],
      created: 1707040459,
      id: 'chatcmpl-tggOnwW8Lp2XiwQ8dmHHAcNYJ8CfzR',
      model: 'gpt-3.5-mock',
      object: 'chat.completion',
      usage: { completion_tokens: 17, prompt_tokens: 57, total_tokens: 74 }
}

The library also supports mocking stream responses

// Call the mockOpenAIResponse function once to set up the mock
mockOpenAIResponse() 
// Now, when you call the OpenAI API, it will return a mock response
const response = await openai.chat.completions.create({
                model: "gpt-3.5",
                stream : true,
                messages: [
                    { role: 'system', content: "You're an expert chef" },
                    { role: 'user', content: "Suggest at least 5 recipes" },
                ]
});

// then read it 
for await (const part of response) {
    console.log(part.choices[0]?.delta?.content || '')
}

Intercepted URLs

This module uses the nock library to intercept HTTP calls to the following OpenAI API endpoints:

https://api.openai.com/v1/chat/completions: This endpoint is used for generating chat completions.
https://api.openai.com/v1/images/generations: This endpoint is used for generating images.

Dependencies

This module depends on the following npm packages:

nock : For intercepting HTTP calls.
@faker-js/faker : For generating fake data.

License

This project is licensed under the MIT License.