write-test

A workflow for writing a failing test that demonstrates a reproduced bug in Metabase, an open-source business-intelligence tool. It chooses among Clojure, Jest, and Cypress tests based on the bug type.

In plain words
What is it for?
Use it to locate the relevant Metabase test file, add a minimal failing test, run it, and save the resulting patch.
Why use it?
It removes the guesswork of finding the right test location and form when turning a bug reproduction into a test.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/metabase/repro-bot/write-test
Any agent
npx skills add metabase/repro-bot --skill write-test
Clone the repo
git clone --depth 1 https://github.com/metabase/repro-bot

Made for: Claude Code, Codex.

Per session 62 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,314 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00062 $0.01314
Opus 5 $0.00031 $0.00657
Sonnet 5 $0.00012 $0.00263
Haiku 4.5 $0.00006 $0.00131

Measured 2d ago against content hash 89a650bb44fb, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

write-test scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.claude/skills/write-test/SKILL.md · 93 lines

How it starts

The opening of the file, as written. The whole thing — 93 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Write Failing Test

This skill is invoked from the /repro workflow. The issue ID, repro dir, reproduction status, and root cause are in conversation context from prior phases.

Determine Test Type

Bug Type Test Type Location
Backend logic, query processor, API Clojure unit test test/metabase/...
Frontend UI behavior, rendering Jest unit/component test frontend/test/... or co-located *.unit.spec.ts/*.unit.spec.tsx
End-to-end user workflow, UI interaction Cypress acceptance test e2e/test/scenarios/...
Mixed (backend + frontend) Both — Clojure test for data + frontend/e2e test for UI

Find Relevant Test File

Use the root cause to identify source file(s), then locate the corresponding test file:

Backend: src/metabase/foo/bar.cljtest/metabase/foo/bar_test.clj Frontend: frontend/src/metabase/foo/Bar.tsxfrontend/src/metabase/foo/Bar.unit.spec.tsx or frontend/test/metabase/foo/Bar.unit.spec.tsx E2E: UI workflow → e2e/test/scenarios/<category>/foo.cy.spec.ts

Use Grep to search for existing tests related to the buggy function/component. Consult CLAUDE.md in the source worktree for test conventions.

Choose Test Approach

Backend (Clojure):

Root Cause Type Test Approach
Query processor bug mt/process-query or qp/process-query
API endpoint bug mt/user-http-request
Model / data bug mt/with-temp + t2/select
Pure logic / edge case Direct function call with specific inputs

Frontend (TypeScript):

Root Cause Type Test Approach
Component rendering bug Jest + React Testing Library — render component, assert DOM
User interaction bug Cypress — visit page, interact, assert visible result
Data display / formatting Jest unit test on the formatting/transform function
State management bug Jest — test reducer/action/selector with specific inputs

Read the full file on GitHub · 93 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 93 lines · 62 tokens per session scan A 89a650bb44fb

Subscribe to this mod's changes

write-test is a skill published in the GitHub repository metabase/repro-bot (10 stars, last pushed 5mo ago), licensed MIT. It adds 62 tokens to every session and 1,314 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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