/test-browser

name: test-browser
description: Run browser tests on pages affected by current PR or branch
argument-hint: "[PR number, branch name, or 'current' for current branch]"

Browser Test Command

<command_purpose>Run end-to-end browser tests on pages affected by a PR or branch changes using agent-browser CLI.</command_purpose>

CRITICAL: Use agent-browser CLI Only

**DO NOT use Chrome MCP tools (mcp__claude-in-chrome__*).**

This command uses the `agent-browser` CLI exclusively. The agent-browser CLI is a Bash-based tool from Vercel that runs headless Chromium. It is NOT the same as Chrome browser automation via MCP.

If you find yourself calling `mcp__claude-in-chrome__*` tools, STOP. Use `agent-browser` Bash commands instead.

Introduction

<role>QA Engineer specializing in browser-based end-to-end testing</role>

This command tests affected pages in a real browser, catching issues that unit tests miss:

• JavaScript integration bugs
• CSS/layout regressions
• User workflow breakages
• Console errors

Prerequisites

<requirements>

• Local development server running (e.g., `bin/dev`, `rails server`, `npm run dev`)
• agent-browser CLI installed (see Setup below)
• Git repository with changes to test

</requirements>

Setup

**Check installation:**

command -v agent-browser >/dev/null 2>&1 && echo "Installed" || echo "NOT INSTALLED"

**Install if needed:**

npm install -g agent-browser
agent-browser install  # Downloads Chromium (~160MB)

See the `agent-browser` skill for detailed usage.

Main Tasks

0. Verify agent-browser Installation

Before starting ANY browser testing, verify agent-browser is installed:

command -v agent-browser >/dev/null 2>&1 && echo "Ready" || (echo "Installing..." && npm install -g agent-browser && agent-browser install)

If installation fails, inform the user and stop.

1. Ask Browser Mode

<ask_browser_mode>

Before starting tests, ask user if they want to watch the browser:

Use AskUserQuestion with:

• Question: "Do you want to watch the browser tests run?"
• Options:

1. **Headed (watch)** - Opens visible browser window so you can see tests run 2. **Headless (faster)** - Runs in background, faster but invisible

Store the choice and use `--headed` flag when user selects "Headed".

</ask_browser_mode>

2. Determine Test Scope

<test_target> $ARGUMENTS </test_target>

<determine_scope>

**If PR number provided:**

gh pr view [number] --json files -q '.files[].path'

**If 'current' or empty:**

git diff --name-only main...HEAD

**If branch name provided:**

git diff --name-only main...[branch]

</determine_scope>

3. Map Files to Routes

<file_to_route_mapping>

Map changed files to testable routes:

| File Pattern | Route(s) | |-------------|----------| | `app/views/users/*` | `/users`, `/users/:id`, `/users/new` | | `app/controllers/settings_controller.rb` | `/settings` | | `app/javascript/controllers/*_controller.js` | Pages using that Stimulus controller | | `app/components/*_component.rb` | Pages rendering that component | | `app/views/layouts/*` | All pages (test homepage at minimum) | | `app/assets/stylesheets/*` | Visual regression on key pages | | `app/helpers/*_helper.rb` | Pages using that helper | | `src/app/*` (Next.js) | Corresponding routes | | `src/components/*` | Pages using those components |

Build a list of URLs to test based on the mapping.

</file_to_route_mapping>

4. Verify Server is Running

<check_server>

Before testing, verify the local server is accessible:

agent-browser open http://localhost:3000
agent-browser snapshot -i

If server is not running, inform user:

**Server not running**

Please start your development server:
- Rails: `bin/dev` or `rails server`
- Node/Next.js: `npm run dev`

Then run `/test-browser` again.

</check_server>

5. Test Each Affected Page

<test_pages>

For each affected route, use agent-browser CLI commands (NOT Chrome MCP):

**Step 1: Navigate and capture snapshot**

agent-browser open "http://localhost:3000/[route]"
agent-browser snapshot -i

**Step 2: For headed mode (visual debugging)**

agent-browser --headed open "http://localhost:3000/[route]"
agent-browser --headed snapshot -i

**Step 3: Verify key elements**

• Use `agent-browser snapshot -i` to get interactive elements with refs
• Page title/heading present
• Primary content rendered
• No error messages visible
• Forms have expected fields

**Step 4: Test critical interactions**

agent-browser click @e1  # Use ref from snapshot
agent-browser snapshot -i

**Step 5: Take screenshots**

agent-browser screenshot page-name.png
agent-browser screenshot --full page-name-full.png  # Full page

</test_pages>

6. Human Verification (When Required)

<human_verification>

Pause for human input when testing touches:

| Flow Type | What to Ask | |-----------|-------------| | OAuth | "Please sign in with [provider] and confirm it works" | | Email | "Check your inbox for the test email and confirm receipt" | | Payments | "Complete a test purchase in sandbox mode" | | SMS | "Verify you received the SMS code" | | External APIs | "Confirm the [service] integration is working" |

Use AskUserQuestion:

**Human Verification Needed**

This test touches the [flow type]. Please:
1. [Action to take]
2. [What to verify]

Did it work correctly?
1. Yes - continue testing
2. No - describe the issue

</human_verification>

7. Handle Failures

<failure_handling>

When a test fails:

1. **Document the failure:**

• Screenshot the error state: `agent-browser screenshot error.png`
• Note the exact reproduction steps

2. **Ask user how to proceed:**

   **Test Failed: [route]**

   Issue: [description]
   Console errors: [if any]

   How to proceed?
   1. Fix now - I'll help debug and fix
   2. Create todo - Add to todos/ for later
   3. Skip - Continue testing