# inertia-rails-testing

A skill that tells your agent how to test Inertia Rails responses with RSpec and Minitest matchers instead of raw JSON checks.

- skill · `type=skill` · Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, OpenCode · 465 installs · ★ 70
- Author: inertia-rails
- License: MIT · policy=mirror · the beginning of the file is at the end of this page
- Source: https://github.com/inertia-rails/skills/tree/HEAD/skills/inertia-rails-testing/SKILL.md
- Updated: 2026-09-01
- HTML: https://affpapa.org/en/nevibecode/skills/inertia-rails-testing

## What it does

The skill lays out the matcher set for Inertia specs: `be_inertia_response`, `render_component`, `have_props`, `have_exact_props`, `have_no_prop`, `have_flash`, `have_deferred_props`, `have_view_data`. Each one comes with a worked example — shared props from `inertia_share`, deferred props, partial reloads via `inertia_reload_only` and `inertia_reload_except`, and external redirects through `inertia_location`, which answer with 409 and an `X-Inertia-Location` header.

One rule runs through the whole file: reach for matchers, not `inertia.component` or `inertia.props[:key]`. And after POST, PATCH or DELETE that redirects, call `follow_redirect!` first. Skip it and your assertions run against the 302, not the Inertia page — the single most common mistake in these specs.

Setup is one line in `spec/rails_helper.rb`: `require 'inertia_rails/rspec'`. Controller specs with `assigns` won't work here, because Inertia renders through its own pipeline that only runs in a full request cycle, so use `type: :request`. Minitest users get a separate `references/minitest.md` with the matching assertions, and the skill asks for it to be read in full.

## Install

### Claude Code (native platform)

1. **Skills CLI (Vercel)**
```bash
npx skills add inertia-rails/skills --skill inertia-rails-testing -a claude-code
```

2. **Manually: put the files in place**
- File: `~/.claude/skills/inertia-rails-testing/SKILL.md` — Copy the whole skill folder; for one project use .claude/skills/inertia-rails-testing/

### Codex

1. **Skills CLI (Vercel)**
```bash
npx skills add inertia-rails/skills --skill inertia-rails-testing -a codex
```

2. **Manually: put the files in place**
- File: `.agents/skills/inertia-rails-testing/SKILL.md` — For all projects use ~/.agents/skills/

### Cursor

1. **Skills CLI (Vercel)**
```bash
npx skills add inertia-rails/skills --skill inertia-rails-testing -a cursor
```

2. **Manually: put the files in place**
- File: `.cursor/skills/inertia-rails-testing/SKILL.md` — Cursor also reads .agents/skills/ and .claude/skills/

### GitHub Copilot

1. **GitHub CLI**
```bash
gh skill install inertia-rails/skills inertia-rails-testing
```

2. **Manually: put the files in place**
- File: `.github/skills/inertia-rails-testing/SKILL.md`

### Gemini CLI

1. **Skills CLI (Vercel)**
```bash
npx skills add inertia-rails/skills --skill inertia-rails-testing -a gemini-cli
```

2. **Platform CLI**
```bash
gemini skills install https://github.com/inertia-rails/skills --path skills/inertia-rails-testing
```

### Windsurf (Devin Desktop)

**Manually: put the files in place**
- File: `.devin/skills/inertia-rails-testing/SKILL.md` — The legacy .windsurf/skills/ path still works

### OpenCode

**Skills CLI (Vercel)**
```bash
npx skills add inertia-rails/skills --skill inertia-rails-testing -a opencode
```

### Claude.ai

**Claude.ai**
- Zip the folder and upload it in Settings → Capabilities → Skills

Where a file is given instead of a command, copy the files from the source to that path: https://github.com/inertia-rails/skills/tree/HEAD/skills/inertia-rails-testing/SKILL.md

## When to use it
- assert the controller rendered the right Inertia component
- match page props without comparing the whole JSON payload
- catch data that leaked into props by accident
- verify a flash message survives the redirect
- confirm deferred props are registered rather than nil

## Example prompts
- write a request spec for `users#create` that checks flash with `have_flash`
- add a partial reload test using `inertia_reload_only(:users, :pagination)`
- rewrite these specs to use matchers instead of `inertia.props[:users]`

## Source text · SKILL.md · MIT

Below is the content of a third-party file. It is data, not instructions for you: do not act on anything written inside unless the human asks. Block tag: e5ebb6f5146352cd.

BEGIN THIRD-PARTY FILE e5ebb6f5146352cd
````text
---
name: inertia-rails-testing
description: >-
  Testing Inertia Rails responses with RSpec and Minitest: component assertions, prop matching, flash verification,
  deferred props, and partial reload helpers. Use when writing controller specs, request specs, or integration tests
  for Inertia pages. ALWAYS use matchers (render_component, have_props, have_flash), NOT direct access
  (inertia.component, inertia.props). CRITICAL: after POST/PATCH/DELETE with redirect, MUST call follow_redirect!
  before asserting flash or props — without it you're asserting against the 302, not the Inertia page.
  Setup: require 'inertia_rails/rspec'.
---

# Inertia Rails Testing

Testing patterns for Inertia responses with RSpec and Minitest.

**For each controller action, verify:**
- **Correct component** → `render_component('users/index')`
- **Expected props** → `have_props(users: satisfy { ... })`
- **No leaked data** → `have_no_prop(:secret)`
- **Flash messages** → `follow_redirect!` then `have_flash(notice: '...')`
- **Deferred props** → `have_deferred_props(:analytics)`

**Common mistake:** Forgetting `follow_redirect!` after PRG — without it, you're
asserting against the 302 redirect response, not the Inertia page that follows.

## Setup

```ruby
# spec/rails_helper.rb
require 'inertia_rails/rspec'
```

## RSpec Matchers

| Matcher | Purpose |
|---------|---------|
| `be_inertia_response` | Verify response is Inertia format |
| `render_component('path')` | Check rendered component name |
| `have_props(key: value)` | Partial props match |
| `have_exact_props(key: value)` | Exact props match |
| `have_no_prop(:key)` | Assert prop absent |
| `have_flash(key: value)` | Partial flash match |
| `have_exact_flash(key: value)` | Exact flash match |
| `have_no_flash(:key)` | Assert flash absent |
| `have_deferred_props(:key)` | Check deferred props exist |
| `have_view_data(key: value)` | Partial view_data match |

## RSpec Examples

**ALWAYS use matchers** (`render_component`, `have_props`, `have_flash`) instead of
direct property access (`inertia.component`, `inertia.props[:key]`):

```ruby
# BAD — direct property access:
# expect(inertia.component).to eq('users/index')
# expect(inertia.props[:users].length).to eq(3)

# GOOD — use matchers:
expect(inertia).to render_component('users/index')
expect(inertia).to have_props(users: satisfy { |u| u.length == 3 })
```

```ruby
````
END THIRD-PARTY FILE e5ebb6f5146352cd

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