Configuration

Midstream uses a midstream.json file in your project root to configure how demos are built and run.

Basic Configuration

{
  "install": "npm install",
  "start": "npm start",
  "test": "npx playwright test {{file}} -g {{grep}}"
}

Configuration Options

install

Command to install dependencies. Runs once when the demo environment starts.

{
  "install": "pnpm install --frozen-lockfile"
}

start

Command to start your application. Should start a development server.

{
  "start": "npm run dev"
}

test

Command template to run tests. Use placeholders for dynamic values:

• {{file}} - The test file path
• {{grep}} - The test name pattern

{
  "test": "npx playwright test {{file}} -g {{grep}}"
}

Environment Variables

Midstream automatically provides certain environment variables:

Variable	Description
MIDSTREAM_RUNNER	Set to true in demo environment
MIDSTREAM_CHECKPOINT	The checkpoint being demonstrated

Example Configurations

Next.js Project

{
  "install": "npm install",
  "start": "npm run dev",
  "test": "npx playwright test {{file}} -g {{grep}}"
}

Vite Project

{
  "install": "pnpm install",
  "start": "pnpm dev",
  "test": "pnpm playwright test {{file}} -g {{grep}}"
}

Monorepo

{
  "install": "pnpm install",
  "start": "pnpm --filter @myapp/web dev",
  "test": "pnpm --filter @myapp/e2e test {{file}} -g {{grep}}"
}