Hot Reload

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Overview

1. Starts your local dev server (e.g., Expo Metro bundler)
2. Creates a secure tunnel to expose it to the internet
3. Runs tests against your pre-built development client
4. Connects the dev client to your local server via deep link

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Supported Frameworks

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Prerequisites

1. Authenticated with Revyl:
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   revyl auth login
   
2. Initialized your project:
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   revyl init
   
3. Built and uploaded a development client to Revyl:
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   # Upload a dev build from your configured platform key
   revyl build upload --platform ios-dev
   
4. Configured hot reload + build mappings in .revyl/config.yaml:
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   build:
     platforms:
       ios-dev:
         app_id: "<your-app-id>"
   
   hotreload:
     default: expo
     providers:
       expo:
         app_scheme: myapp
         platform_keys:
           ios: ios-dev
   

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Quick Start

# 1. One-time setup (auto-detects your project)
revyl init --hotreload

# 2. Run a test with hot reload
revyl test run login-flow --hotreload --platform ios

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Setup Guide

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Automatic Setup

revyl init --hotreload

• Detect your project type (Expo, Swift, Android)
• Extract configuration from your project files (e.g., app.json)
• Save the configuration to .revyl/config.yaml

Detecting project types...

Found 1 compatible provider(s):
  ✓ Expo (confidence: 0.9)
    - app.json
    - expo in package.json

Setting up Expo...
✓ Auto-detected app scheme: myapp (from app.json)
✓ Expo configured!

Configuration saved!

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Manual Configuration

hotreload:
  default: expo
  providers:
    expo:
      port: 8081
      app_scheme: myapp

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Usage

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Running Tests with Hot Reload

# Run an existing test
revyl test run login-flow --hotreload --platform ios

# Create a new test with hot reload session
revyl test create checkout-flow --hotreload --platform-key ios-dev --platform ios

# Open an existing test in the editor with hot reload
revyl test open login-flow --hotreload --platform-key ios-dev

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Specifying the Build

revyl test run login-flow --hotreload --platform ios

revyl test run login-flow --hotreload --build-version-id abc123-def456

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Branch-first dev build flow

git checkout -b feature/new-login
revyl build upload --platform ios-dev
revyl dev --platform ios

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Direct-file upload flow (--skip-build)

1. Set build.platforms.<key>.output to the artifact path.
2. Upload with --skip-build.
3. Start your dev/test hot reload flow.

build:
  platforms:
    ios-dev:
      app_id: "<your-app-id>"
      output: "./dist/MyApp.ipa" # or .apk

revyl build upload --platform ios-dev --skip-build
revyl dev --platform ios

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Overriding the Port

revyl test run login-flow --hotreload --platform ios --port 8082

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Multiple Providers

revyl test run login-flow --hotreload --provider expo --platform ios

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Configuration Reference

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Full Schema

hotreload:
  # Default provider when --provider flag is not specified
  default: expo
  
  providers:
    expo:
      # Port for the Expo dev server (default: 8081)
      port: 8081
      
      # URL scheme from your app.json (required)
      # This is used to construct deep links
      app_scheme: myapp
      
      # Whether to use "exp+" prefix in deep links (default: false)
      # Set to true if your dev client was built with addGeneratedScheme: true
      use_exp_prefix: false

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Configuration Options

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The use_exp_prefix Option

• Base scheme: myapp:// (default, works with most builds)
• Prefixed scheme: exp+myapp:// (newer Expo convention)

hotreload:
  providers:
    expo:
      app_scheme: myapp
      use_exp_prefix: true

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How It Works

┌─────────────────┐     ┌──────────────────┐     ┌─────────────────┐
│  Your Machine   │     │ Cloudflare Tunnel│     │  Revyl Device   │
│                 │     │                  │     │                 │
│  ┌───────────┐  │     │                  │     │  ┌───────────┐  │
│  │ Expo Dev  │──┼─────┼──────────────────┼─────┼──│ Dev Client│  │
│  │  Server   │  │     │  Secure Tunnel   │     │  │   Build   │  │
│  │ :8081     │  │     │                  │     │  │           │  │
│  └───────────┘  │     │                  │     │  └───────────┘  │
│                 │     │                  │     │                 │
│  ┌───────────┐  │     │                  │     │  ┌───────────┐  │
│  │ Revyl CLI │──┼─────┼──────────────────┼─────┼──│   Test    │  │
│  │           │  │     │   API Calls      │     │  │ Execution │  │
│  └───────────┘  │     │                  │     │  └───────────┘  │
└─────────────────┘     └──────────────────┘     └─────────────────┘

1. CLI starts the dev server: Runs npx expo start --dev-client
2. Tunnel is created: A Cloudflare quick tunnel exposes your local server
3. Deep link is constructed: {scheme}://expo-development-client/?url={tunnel-url}
4. Test runs: The dev client opens via deep link and connects to your server
5. Live updates: Any code changes are instantly reflected via Metro’s hot reload

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Troubleshooting

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Deep Link Not Working

1. Verify your app_scheme matches the scheme in your app.json
2. Try setting use_exp_prefix: true in your config
3. Ensure your dev client build has the URL scheme registered

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Port Already in Use

1. Kill any existing Metro processes: killall node or lsof -ti:8081 | xargs kill
2. Use a different port: --port 8082
3. The CLI attempts to clean up on exit, but interrupted sessions may leave processes running

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Tunnel Connection Issues

1. Check your internet connection
2. Some corporate networks block tunneling services—try from a different network
3. The CLI will show diagnostic information if the tunnel fails

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White Screen After Connecting

1. Check the Metro bundler output for JavaScript errors
2. Ensure your dev client build matches your current Expo SDK version
3. Try restarting the hot reload session

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Build Platform Not Found

build:
  platforms:
    ios-dev:
      app_id: "<your-app-id>"

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Best Practices

1. Use a dedicated dev client build: Create a separate build platform for hot reload testing
2. Keep your dev client updated: Rebuild when you update Expo SDK or native dependencies
3. Use consistent ports: Stick to the default port (8081) unless you have conflicts
4. Clean up sessions: Use Ctrl+C to properly terminate hot reload sessions

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Next Steps

• Dev Loop overview
• Create your first test →
• Set up build platforms →
• Expo integration →
• CLI reference →