Issue 13 · 17 Sep 2026 · Medium · Free
Test Plan from the Prompt
The feature works on the happy path you described to the model, and the cases you never mentioned are still untested.
Paste the prompt you used to vibe-code a feature. Get the checks to run before merge, including the case that prompt forgot.
- Category
- Coding & Vibe Coding
- Runs in
- Cursor
- Claude
- ChatGPT
What you put in and what you get out
You put in
Paste the original prompt. Use the prompt you gave the coding agent, not a cleaned-up spec you wrote afterward. The gaps in that prompt are the point.
Agent
Test Plan from the Prompt
You get out
Later. The 7-day boundary and the hidden button are listed as follow-ups, not pretended to be done.
Sample you can paste
Prompt I gave Cursor: "Add a refund button on the order page. If the order is paid and less than 7 days old, call POST /api/refunds with the order id. Show a toast on success." What shipped: the button, the fetch, a toast that says Refunded. I did not mention: failed requests, double clicks, orders that are already refunded, or who is allowed to see the button. Stack: Next.js, the button is a client component.
Share this agent
Test Plan from the Prompt — You put in Prompt I gave Cursor:. You get out Later. Free from One Agent a Day.
30-second demo
0:00
The original prompt
A refund button for paid orders under 7 days, a POST, and a success toast. No failure, no double click, no permissions.
How it works
The prompt you used to generate the feature is a spec with holes. This agent reads that prompt and names the cases it never mentioned, then turns the dangerous ones into checks you can run before merge.
It does not write a novel of tests, and it does not claim a case passes. Each check has a setup, an action, and a visible result. Cases you already said were tested are left off the before-merge list.
Run the three. If one fails, that is the plan working. Do not paste a production token into the chat to try the call.
Use it
Step 1
Paste the original prompt
Use the prompt you gave the coding agent, not a cleaned-up spec you wrote afterward. The gaps in that prompt are the point.
Step 2
Add what actually shipped
Two or three lines: what exists now, and the stack. If a case is already tested, say so and the plan will skip it.
Step 3
Paste this agent's prompt first
You get a short list of checks. Each one says the setup, the action, and the result you should see.
Step 4
Run the first three
Do not try to automate the whole list in one sitting. Run the three the agent marks as before-merge. File the rest.
Prompt
test-plan-from-prompt.prompt.txt
You write a test plan from the prompt a person used to vibe-code a feature. You look for the cases that prompt forgot.
INPUTS
- Original prompt: the text they gave the coding agent.
- What shipped: a short description.
- Already tested: optional.
RULES
- Derive cases from missing words in the original prompt: failure, repeat, permission, empty, boundary, and the opposite of the happy path.
- Do not invent product rules they did not state. A boundary they did state (like 7 days) is in scope. A rule they did not state is a question, not a test.
- Mark exactly 3 checks as before-merge. The rest are later.
- Each check: setup, action, result you can see. No exploit steps. No production secrets.
- Skip anything they listed as already tested.
- Cap the whole plan at 8 checks.
OUTPUT
## Forgot
The cases the original prompt never mentioned.
## Before merge
3 checks. Numbered.
## Later
The rest.
## Questions
Rules you refused to invent, as questions.Related agents
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