dependency-upgrade

# Dependency Upgrade

Master major dependency version upgrades, compatibility analysis, staged upgrade strategies, and comprehensive testing approaches.

## When to Use This Skill

- Upgrading major framework versions
- Updating security-vulnerable dependencies
- Modernizing legacy dependencies
- Resolving dependency conflicts
- Planning incremental upgrade paths
- Testing compatibility matrices
- Automating dependency updates

## Semantic Versioning Review

```
MAJOR.MINOR.PATCH (e.g., 2.3.1)

MAJOR: Breaking changes
MINOR: New features, backward compatible
PATCH: Bug fixes, backward compatible

^2.3.1 = >=2.3.1 <3.0.0 (minor updates)
~2.3.1 = >=2.3.1 <2.4.0 (patch updates)
2.3.1 = exact version
```

## Dependency Analysis

### Audit Dependencies
```bash
# npm
npm outdated
npm audit
npm audit fix

# yarn
yarn outdated
yarn audit

# Check for major updates
npx npm-check-updates
npx npm-check-updates -u  # Update package.json
```

### Analyze Dependency Tree
```bash
# See why a package is installed
npm ls package-name
yarn why package-name

# Find duplicate packages
npm dedupe
yarn dedupe

# Visualize dependencies
npx madge --image graph.png src/
```

## Compatibility Matrix

```javascript
// compatibility-matrix.js
const compatibilityMatrix = {
  'react': {
    '16.x': {
      'react-dom': '^16.0.0',
      'react-router-dom': '^5.0.0',
      '@testing-library/react': '^11.0.0'
    },
    '17.x': {
      'react-dom': '^17.0.0',
      'react-router-dom': '^5.0.0 || ^6.0.0',
      '@testing-library/react': '^12.0.0'
    },
    '18.x': {
      'react-dom': '^18.0.0',
      'react-router-dom': '^6.0.0',
      '@testing-library/react': '^13.0.0'
    }
  }
};

function checkCompatibility(packages) {
  // Validate package versions against matrix
}
```

## Staged Upgrade Strategy

### Phase 1: Planning
```bash
# 1. Identify current versions
npm list --depth=0

# 2. Check for break