testing

A set of testing rules for a Rails application using Minitest. Minitest is Ruby's testing framework, while fixtures provide prepared test data and Capybara with Selenium drives browser-based tests.

In plain words
What is it for?
Use it when adding tests for models, controllers, services, system workflows, or regressions. It also defines how to set up tests, assert results, use fixtures, and stub external APIs.
Why use it?
It makes changes and bug fixes easier to verify and prevents tests from depending on live external services or inconsistent test structure.

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/romkey/i2c-directory/testing
Clone the repo
git clone --depth 1 https://github.com/romkey/I2C-Directory

Made for: Cursor.

Per session 0 Nothing until a file matches its globs; then the whole rule loads.
When invoked 280 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 $0.00280
Opus 5 $0.00000 $0.00140
Sonnet 5 $0.00000 $0.00056
Haiku 4.5 $0.00000 $0.00028

Measured yesterday against content hash d5deb44f0750, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

testing 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/testing.mdc · 35 lines

What it actually says

Testing

  • Framework: Minitest 5 with Rails test helpers
  • Fixtures: YAML fixtures in test/fixtures/; fixtures :all is set in test_helper.rb
  • Parallelization: Tests run in parallel by processor count
  • Run tests: docker compose -f docker-compose.test.yml run --rm test

Conventions

  • Write tests for every change; write regression tests for every bug fix
  • Place model tests in test/models/, controller tests in test/controllers/, service tests in test/services/
  • Use assert_* methods, not RSpec-style expect
  • Use setup and teardown methods for test lifecycle, not before/after
  • System tests use Capybara with Selenium Chrome — place in test/system/
  • Stub external API calls (OIDC provider, etc.) in tests — never hit real APIs
# ✅ Standard test structure
class MemberTest < ActiveSupport::TestCase
  setup do
    @member = members(:active_member)
  end

  test 'should be valid with required attributes' do
    assert @member.valid?
  end
end
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 · 35 lines · 0 tokens per session scan A d5deb44f0750

Subscribe to this mod's changes

testing is a cursor rule published in the GitHub repository romkey/I2C-Directory (11 stars, last pushed 21d ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 280 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 2026-08-30.