react-component-hook-testing-auto

A set of rules for unit-testing React components and custom hooks with React Testing Library and Vitest. It emphasizes user-visible behavior, accessibility-based queries, typed code, and cleanup.

In plain words
What is it for?
Use it to write or review tests for React components and hooks, including rendering, user actions, accessibility, mocked dependencies, and asynchronous behavior.
Why use it?
It helps avoid brittle tests that depend on private component details, while ensuring interactions, assertions, edge cases, and side effects are covered.

Cursor rule for Cursor

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 rules/usrrname/cursorrules/react-component-hook-testing-auto
Clone the repo
git clone --depth 1 https://github.com/usrrname/cursorrules

Made for: Cursor.

Per session 0 Nothing until a file matches its globs; then the whole rule loads.
When invoked 1,159 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 $0.00000 $0.01159
Opus 5 $0.00000 $0.00580
Sonnet 5 $0.00000 $0.00232
Haiku 4.5 $0.00000 $0.00116

Measured yesterday against content hash 69d8b7f9e0e2, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

react-component-hook-testing-auto 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 yesterday.

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.

.cursor/rules/test/react-component-hook-testing-auto.mdc · 123 lines

How it starts

The opening of the file, as written. The whole thing — 123 lines — stays where its author put it; the contents beside it link to each section on GitHub.

React Unit Testing Standards

Critical Rules

  • Use @testing-library/react for rendering components; avoid shallow rendering or testing implementation details.
  • Prefer accessibility queries (getByRole, getByLabelText, etc.) over getByTestId or CSS selectors.
  • Simulate user interactions with userEvent instead of firing raw DOM events.
  • Each test must contain at least one assertion using expect.
  • Group related tests in describe blocks with descriptive titles.
  • Avoid querying private DOM nodes with container.querySelector.
  • Do not snapshot the entire DOM tree for dynamic components; assert specific, stable text/attributes.
  • For hooks, use @testing-library/react's renderHook or equivalent utilities.
  • Always test custom hooks in isolation and with all relevant edge cases.
  • Mock external dependencies and context providers as needed for hooks.
  • Avoid using any in test or hook typings; always use explicit types.
  • Clean up side-effects after each test (rely on library auto-cleanup or call cleanup()).
  • Do not use .skip or .only in committed test code.

Read the full file on GitHub · 123 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. yesterday First seen · 123 lines · 0 tokens per session scan A 69d8b7f9e0e2

Subscribe to this mod's changes

react-component-hook-testing-auto is a cursor rule published in the GitHub repository usrrname/cursorrules (10 stars, last pushed 4mo ago), licensed ISC. It costs nothing until one of its globs matches a file; then it loads 1,159 tokens. 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.