test(danger): Add comprehensive tests for extra-dangerfile and extra-install-packages features

Add test coverage for the new extra-dangerfile and extra-install-packages inputs:

- Create test-dangerfile.js demonstrating custom Danger checks
- Add extra-dangerfile-test job to verify custom dangerfiles execute correctly
- Add extra-packages-test job to verify package installation works
- Tests validate that custom dangerfiles can access the Danger API and installed packages

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: vaind

.github/test-dangerfile.js

@@ -0,0 +1,37 @@
+// Test dangerfile for exercising extra-dangerfile feature
+// This demonstrates how repositories can add custom Danger checks
+
+module.exports = async function ({ fail, warn, message, markdown, danger }) {
+  console.log('::notice::Running custom dangerfile checks...');
+
+  // Test that we have access to the danger API
+  if (!danger || !danger.github || !danger.github.pr) {
+    fail('Custom dangerfile cannot access danger API');
+    return;
+  }
+
+  // Example check: Verify PR has a description
+  const prBody = danger.github.pr.body;
+  if (!prBody || prBody.trim().length === 0) {
+    warn('PR description is empty. Consider adding a description to help reviewers.');
+  } else {
+    message('✅ Custom dangerfile check: PR has a description');
+  }
+
+  // Example check: Verify PR title is not too short
+  const prTitle = danger.github.pr.title;
+  if (prTitle && prTitle.length < 10) {
+    warn('PR title is quite short. Consider making it more descriptive.');
+  } else {
+    message('✅ Custom dangerfile check: PR title length is reasonable');
+  }
+
+  // Show that we can access git information
+  const modifiedFiles = danger.git.modified_files || [];
+  const createdFiles = danger.git.created_files || [];
+  const totalChangedFiles = modifiedFiles.length + createdFiles.length;
+
+  message(`📊 Custom check: This PR changes ${totalChangedFiles} file(s)`);
+
+  console.log('::notice::Custom dangerfile checks completed successfully');
+};

.github/workflows/danger-workflow-tests.yml

@@ -34,3 +34,70 @@ jobs:
 
           Write-Host "✅ Danger PR analysis completed successfully!"
           Write-Host "ℹ️  Check the PR comments for any Danger findings"
+
+  # Test extra-dangerfile feature
+  extra-dangerfile-test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Run danger with extra dangerfile
+        id: danger-extra
+        uses: ./danger
+        with:
+          extra-dangerfile: '.github/test-dangerfile.js'
+
+      - name: Validate danger with extra-dangerfile outputs
+        env:
+          DANGER_OUTCOME: ${{ steps.danger-extra.outputs.outcome }}
+        shell: pwsh
+        run: |
+          Write-Host "🔍 Validating Danger action with extra-dangerfile..."
+          Write-Host "Danger Outcome: '$env:DANGER_OUTCOME'"
+
+          # Validate that Danger ran successfully
+          $env:DANGER_OUTCOME | Should -Be "success"
+
+          Write-Host "✅ Danger with extra-dangerfile completed successfully!"
+
+  # Test extra-install-packages feature
+  extra-packages-test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      # Create a test dangerfile that requires curl
+      - name: Create test dangerfile requiring curl
+        shell: bash
+        run: |
+          cat > .github/test-dangerfile-curl.js << 'EOF'
+          module.exports = async function ({ message, danger }) {
+            const { execSync } = require('child_process');
+            try {
+              const curlVersion = execSync('curl --version', { encoding: 'utf-8' });
+              message('✅ curl is available: ' + curlVersion.split('\n')[0]);
+            } catch (err) {
+              throw new Error('curl command not found - extra-install-packages failed');
+            }
+          };
+          EOF
+
+      - name: Run danger with extra packages
+        id: danger-packages
+        uses: ./danger
+        with:
+          extra-dangerfile: '.github/test-dangerfile-curl.js'
+          extra-install-packages: 'curl'
+
+      - name: Validate danger with extra-install-packages outputs
+        env:
+          DANGER_OUTCOME: ${{ steps.danger-packages.outputs.outcome }}
+        shell: pwsh
+        run: |
+          Write-Host "🔍 Validating Danger action with extra-install-packages..."
+          Write-Host "Danger Outcome: '$env:DANGER_OUTCOME'"
+
+          # Validate that Danger ran successfully
+          $env:DANGER_OUTCOME | Should -Be "success"
+
+          Write-Host "✅ Danger with extra-install-packages completed successfully!"