What is rails-testing?

A guide to testing Ruby on Rails applications with RSpec, a tool for writing automated tests in Ruby. It covers tests for models, web requests, user journeys, background jobs, test data, and test-suite organisation.

It helps create, review, or refactor RSpec tests, FactoryBot test data, Capybara browser tests, Sidekiq or Active Job tests, shared examples, and custom matchers.

It helps developers write tests that are easier to maintain and less likely to be slow or unreliable. It also points out common testing mistakes and ways to improve coverage and speed.

rails-testing — Skill for Claude Code and Codex by pproenca/dot-skills

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.

Any agent

npx skills add pproenca/dot-skills --skill rails-testing

Clone the repo

git clone --depth 1 https://github.com/pproenca/dot-skills

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/skills/pproenca/dot-skills/rails-testing/github.svg)](https://agentmods.dev/skills/pproenca/dot-skills/rails-testing)

Your own site

<a href="https://agentmods.dev/skills/pproenca/dot-skills/rails-testing"><img src="https://agentmods.dev/badge/skills/pproenca/dot-skills/rails-testing/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/skills/pproenca/dot-skills/rails-testing"><img src="https://agentmods.dev/badge/skills/pproenca/dot-skills/rails-testing.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 103 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 1,882 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits

NVIDIA SkillSpector pass 7 Sept 2026

How audits are shown

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.

Model	Per session	Once invoked
Fable 5.1	$0.00103	$0.01882
Opus 5.5	$0.00041	$0.00753
Sonnet 5.5	$0.00021	$0.00376
Haiku 4.5	$0.00010	$0.00188

Measured 2mo ago against content hash 72c4ee44e945, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

rails-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 2mo 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.

skills/.curated/rails-testing/SKILL.md · 120 lines

How it starts

The opening of the file, as written. The whole thing — 120 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Community Ruby on Rails Testing Best Practices

Comprehensive testing guide for Ruby on Rails applications, maintained by Community. Contains 46 rules across 8 categories, prioritized by impact to guide automated test generation, review, and refactoring.

When to Apply

Reference these guidelines when:

Writing new RSpec specs for models, requests, system tests, or jobs
Setting up FactoryBot factories with traits and sequences
Writing Capybara system tests for user journeys
Testing background jobs with Sidekiq or Active Job
Reviewing test code for anti-patterns (mystery guests, flaky tests, slow specs)
Optimizing test suite performance and CI pipeline speed
Organizing test files, shared examples, and custom matchers

Rule Categories by Priority

Priority	Category	Impact	Prefix
1	Test Design & Structure	CRITICAL	`design-`
2	Test Data Management	CRITICAL	`data-`
3	Model Testing	HIGH	`model-`
4	Request & Controller Testing	HIGH	`request-`
5	System & Acceptance Testing	MEDIUM-HIGH	`system-`
6	Async & Background Job Testing	MEDIUM	`async-`
7	Test Performance & Reliability	MEDIUM	`perf-`
8	Test Organization & Maintenance	LOW-MEDIUM	`org-`

Quick Reference

1. Test Design & Structure (CRITICAL)

design-four-phase-test - Use four-phase test structure (setup, exercise, verify, teardown)
design-behavior-over-implementation - Test observable behavior, not internal implementation
design-one-assertion-per-test - One logical expectation per test for precise failure diagnosis
design-descriptive-test-names - Write test names that read like specifications
design-avoid-mystery-guest - Make all test data visible within the test itself
design-avoid-conditional-logic - No if/else or loops in test code
design-explicit-subject - Name subjects explicitly instead of using implicit subject

Read the full file on GitHub · 120 lines

Files

What ships with it

50 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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.

2mo ago First seen · 120 lines · 103 tokens per session scan A 72c4ee44e945

Subscribe to this mod's changes

rails-testing is a skill published in the GitHub repository pproenca/dot-skills (221 stars, last pushed 2mo ago), licensed MIT. It adds 103 tokens to every session and 1,882 once invoked, about $0.0004 per session on Opus 5.5. 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 2026-08-30.

Languages Ruby Testing Unit testing

rspec-conventions

Rootstrap RSpec conventions. Use when writing, reviewing, or editing RSpec test files (spec//spec.rb, spec/railshelper.rb, spec/spechelper.rb, spec/support//.rb) or factories. Covers describe/context structure, let/subject, matchers, factories, mocking/stubbing, shared examples, and spec types (model, request…

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testunit-skill

Generates Test::Unit tests in Ruby. Classic xUnit-style testing with assert methods and test case classes. Use when user mentions "Test::Unit", "assertequal Ruby", "Ruby test-unit". Triggers on: "Test::Unit", "Ruby test-unit", "assertequal Ruby" (not RSpec).

LambdaTest/agent-skills · 70 tokens

rails-testing