Add GitHub Action to install latest stable DSCv3

.eslintrc.json

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+{
+  "extends": "./node_modules/@typescript-eslint/eslint-plugin/dist/configs/recommended.js",
+  "parser": "@typescript-eslint/parser",
+  "plugins": ["@typescript-eslint"],
+  "rules": {
+    "@typescript-eslint/no-require-imports": "error",
+    "@typescript-eslint/no-unused-vars": "error",
+    "@typescript-eslint/explicit-function-return-type": [
+      "error",
+      {
+        "allowExpressions": true
+      }
+    ],
+    "semi": ["error", "never"],
+    "no-console": "warn"
+  },
+  "env": {
+    "node": true,
+    "es6": true
+  }
+}

.github/workflows/ci.yml

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+name: CI
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+    branches:
+      - main
+
+jobs:
+  build:
+    name: Build and Test
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: '20'
+          cache: 'npm'
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: Lint
+        run: npm run lint
+
+      - name: Build
+        run: npm run build
+
+      - name: Test
+        run: npm test
+
+      - name: Package
+        run: npm run package
+
+      - name: Verify dist is up to date
+        run: |
+          if [ "$(git diff --ignore-space-at-eol dist/ | wc -l)" -gt "0" ]; then
+            echo "Detected uncommitted changes after build. Please run 'npm run all' and commit the changes."
+            git diff --ignore-space-at-eol dist/
+            exit 1
+          fi
+
+  test-action:
+    name: Test Action (Linux)
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Run setup-dsc action
+        uses: ./
+        id: setup-dsc
+
+      - name: Verify DSC installed
+        run: dsc --version
+
+      - name: Print installed version
+        run: echo "DSC version ${{ steps.setup-dsc.outputs.dsc-version }} installed"
+
+  test-action-windows:
+    name: Test Action (Windows)
+    runs-on: windows-latest
+    permissions:
+      contents: read
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Run setup-dsc action
+        uses: ./
+        id: setup-dsc
+
+      - name: Verify DSC installed
+        run: dsc --version
+
+      - name: Print installed version
+        run: echo "DSC version ${{ steps.setup-dsc.outputs.dsc-version }} installed"
+
+  test-action-macos:
+    name: Test Action (macOS)
+    runs-on: macos-latest
+    permissions:
+      contents: read
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Run setup-dsc action
+        uses: ./
+        id: setup-dsc
+
+      - name: Verify DSC installed
+        run: dsc --version
+
+      - name: Print installed version
+        run: echo "DSC version ${{ steps.setup-dsc.outputs.dsc-version }} installed"

.gitignore

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+node_modules/
+lib/
+*.js.map
+coverage/

README.md

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 # setup-dsc
 GitHub Action for installing DSCv3
+
+## Usage
+
+### Install the latest stable DSC
+
+```yaml
+- name: Setup DSC
+  uses: PowerShell/setup-dsc@v1
+```
+
+### Install a specific version of DSC
+
+```yaml
+- name: Setup DSC
+  uses: PowerShell/setup-dsc@v1
+  with:
+    dsc-version: '3.0.0'
+```
+
+## Inputs
+
+| Name | Description | Default |
+|------|-------------|---------|
+| `dsc-version` | Version of DSC to install. Supports exact versions (e.g. `3.0.0`) or `latest` to get the latest stable release. | `latest` |
+
+## Outputs
+
+| Name | Description |
+|------|-------------|
+| `dsc-version` | The version of DSC that was installed |
+
+## Supported Platforms
+
+| OS | Architecture |
+|----|-------------|
+| Windows | x64, arm64 |
+| Linux | x64, arm64 |
+| macOS | x64, arm64 |
+
+## Example Workflow
+
+```yaml
+name: DSC Configuration
+
+on: [push]
+
+jobs:
+  configure:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Setup DSC
+        uses: PowerShell/setup-dsc@v1
+        id: setup-dsc
+
+      - name: Verify DSC version
+        run: dsc --version
+
+      - name: Apply configuration
+        run: dsc config apply --path ./config.dsc.yaml
+```
+
+## License
+
+This project is licensed under the MIT License. See [LICENSE](LICENSE) for details.

__tests__/installer.test.ts

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+import {getAssetName, getDownloadUrl} from '../src/utils'
+
+describe('installer', () => {
+  describe('asset name generation', () => {
+    it('should generate correct asset name for windows x64', () => {
+      const name = getAssetName('3.0.0', 'windows', 'x86_64')
+      expect(name).toBe('DSC-3.0.0-x86_64-pc-windows-msvc.zip')
+    })
+
+    it('should generate correct asset name for linux x64', () => {
+      const name = getAssetName('3.0.0', 'linux', 'x86_64')
+      expect(name).toBe('DSC-3.0.0-x86_64-unknown-linux-gnu.tar.gz')
+    })
+
+    it('should generate correct asset name for darwin x64', () => {
+      const name = getAssetName('3.0.0', 'darwin', 'x86_64')
+      expect(name).toBe('DSC-3.0.0-x86_64-apple-darwin.tar.gz')
+    })
+
+    it('should generate correct asset name for darwin arm64', () => {
+      const name = getAssetName('3.0.0', 'darwin', 'aarch64')
+      expect(name).toBe('DSC-3.0.0-aarch64-apple-darwin.tar.gz')
+    })
+
+    it('should generate correct asset name for linux arm64', () => {
+      const name = getAssetName('3.0.0', 'linux', 'aarch64')
+      expect(name).toBe('DSC-3.0.0-aarch64-unknown-linux-gnu.tar.gz')
+    })
+
+    it('should throw for unsupported platform', () => {
+      expect(() => getAssetName('3.0.0', 'freebsd', 'x86_64')).toThrow(
+        'Unsupported platform: freebsd'
+      )
+    })
+  })
+
+  describe('download URL generation', () => {
+    it('should generate correct download URL', () => {
+      const url = getDownloadUrl(
+        '3.0.0',
+        'DSC-3.0.0-x86_64-pc-windows-msvc.zip'
+      )
+      expect(url).toBe(
+        'https://github.com/PowerShell/DSC/releases/download/v3.0.0/DSC-3.0.0-x86_64-pc-windows-msvc.zip'
+      )
+    })
+  })
+})

action.yml

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+name: 'Setup DSC'
+description: 'Install the latest stable DSCv3 package and add it to the PATH'
+author: 'Microsoft Corporation'
+
+inputs:
+  dsc-version:
+    description: 'Version of DSC to install. Defaults to latest stable.'
+    required: false
+    default: 'latest'
+
+outputs:
+  dsc-version:
+    description: 'The version of DSC that was installed'
+
+runs:
+  using: 'node20'
+  main: 'dist/index.js'
+
+branding:
+  icon: 'package'
+  color: 'blue'

jest.config.json

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+{
+  "preset": "ts-jest",
+  "testEnvironment": "node",
+  "testMatch": ["**/__tests__/**/*.test.ts"],
+  "transform": {
+    "^.+\\.ts$": "ts-jest"
+  },
+  "verbose": true,
+  "clearMocks": true
+}