LLM Test Kit: The Essential Testing Suite for LLM-Powered Applications

llm-test-kit is an innovative testing tool designed specifically for developers creating AI-powered applications. It addresses crucial concerns such as the consistency of responses, latency, cost per request, and overall behavior of LLM (Large Language Model) outputs. By providing a comprehensive solution, this tool helps developers ensure their models function correctly before deployment, significantly enhancing reliability and performance.

Key Features

llm-test-kit runs important tests on any LLM prompt with support for OpenAI and Anthropic models. The tool includes four main tests:

At the conclusion of tests, a detailed visual HTML report can be generated with just one command, allowing for easy review and analysis.

Quick Start Guide

To quickly run tests using llm-test-kit:

1. Check Provider Connectivity:

   node bin/cli.js ping
   

2. Run All Tests and Generate a Report:

   node bin/report.js -p "What is an API?" --runs 3 --contains "interface"
   open report.html
   

3. Execute Individual Tests with Commands:
   • To assess consistency:

     node bin/cli.js consistency -p "Explain APIs" --runs 3
     

   • To measure latency:

     node bin/cli.js latency -p "Explain APIs" --runs 5
     

   • To evaluate costs:

     node bin/cli.js cost -p "Explain APIs" --runs 3 --budget 0.50
     

   • To verify behavior:

     node bin/cli.js behavior -p "List 3 languages" --contains "Python" --min-length 50
     

Example Output

When testing llm-test-kit against the prompt "What is an API?", results could look like this:

Consistency score : D (60) — content consistent, formatting varies
Latency avg       : 6823ms — Grade F for this prompt length
Cost total        : $0.014418 across 3 runs — zero spikes
Behavior          : 2/2 assertions passed

This tool crucially highlights insights such as stability in outputs despite variations in formatting, allowing developers to refine their prompts for optimal performance.

Supported Providers and Models

Currently, llm-test-kit supports:

• Anthropic: claude-sonnet-4-6, claude-opus-4-6
• OpenAI: gpt-4o, gpt-4o-mini

Why Use LLM Test Kit?

With llm-test-kit, developers gain confidence in their LLM implementations by effectively managing key questions about output consistency, API costs, and behavior validation. This open-source tool fills a significant gap by providing the essential resources needed to construct robust AI applications.

Future Development

A roadmap is in place for further enhancements, including support for additional providers, side-by-side comparisons, and CI/CD integration to ensure consistency across deployments.

Contribution

Contributions are encouraged. For those interested, check the CONTRIBUTING.md for guidelines or open an issue to report bugs or suggest features.

By leveraging llm-test-kit, developers can elevate their AI-powered apps with enhanced testing and monitoring, ultimately leading to a more reliable user experience.