Unit Test Writer Prompt for ChatGPT & Claude

This is a free, ready-made prompt for chatgpt & claude that tests that cover the edge cases you would forget, not just the happy path. Copy it, replace the bracketed parts, and paste it into your AI — no login and no cost.

The prompt — for ChatGPT, Gemini & DeepSeek

✎ Editable — click in, customize or extend this prompt, then copy. Your edits copy with it.

The prompt — Claude version

Same prompt, structured with the XML tags Claude follows most reliably.

✎ Editable — click in, customize or extend this prompt, then copy. Your edits copy with it.

This prompt for your model

ChatGPT version Claude version Gemini version DeepSeek version Grok version Mistral Le Chat version Llama version Copilot version Perplexity version Qwen version Kimi version GLM version

How to use this prompt

Replace the bracketed placeholders — [PASTE THE FUNCTION OR CODE], [LANGUAGE AND TEST FRAMEWORK] — with your own details, then paste the whole prompt as your first message. The bracketed parts are the only editing needed; the instructions around them are what make the answer come back structured instead of vague. If the first result is close but not right, ask the AI to adjust one thing at a time rather than rewriting the prompt.

Want a different version of this prompt?

Open the prompt gateway and type your goal in one line — it builds a fresh prompt around your exact wording, formatted for whichever model you run, with your choice of tone and output format.