Add comprehensive test suite with Jest and GitHub Actions

- Added Jest test framework with 29 unit tests
- Achieved 100% code coverage
- Refactored core logic into testable lib/mdtail.js module
- Created GitHub Actions workflow for automated testing
- Configured Coveralls integration for coverage reporting
- Tests cover argument parsing, file handling, navigation, and display
- Added test scripts: test, test:watch, test:coverage

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

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

Author: super3

.github/workflows/test.yml

@@ -0,0 +1,35 @@
+name: Tests
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    
+    steps:
+    - name: Checkout repository
+      uses: actions/checkout@v4
+    
+    - name: Setup Node.js
+      uses: actions/setup-node@v4
+      with:
+        node-version: '22.x'
+        cache: 'npm'
+    
+    - name: Install dependencies
+      run: npm ci
+    
+    - name: Run tests
+      run: npm test
+    
+    - name: Generate coverage report
+      run: npm run test:coverage
+    
+    - name: Upload coverage to Coveralls
+      uses: coverallsapp/github-action@v2
+      with:
+        github-token: ${{ secrets.GITHUB_TOKEN }}

.gitignore

@@ -1,4 +1,7 @@
 node_modules/
+coverage/
 .DS_Store
 *.log
-.env
+.env
+.vscode/
+.idea/

jest.config.js

@@ -0,0 +1,13 @@
+module.exports = {
+  testEnvironment: 'node',
+  collectCoverageFrom: [
+    'lib/**/*.js',
+    '!lib/**/*.test.js'
+  ],
+  coverageDirectory: 'coverage',
+  coverageReporters: ['text', 'lcov', 'html'],
+  testMatch: [
+    '**/test/**/*.test.js'
+  ],
+  verbose: true
+};

lib/mdtail.js

@@ -0,0 +1,122 @@
+const fs = require('fs');
+const path = require('path');
+
+class MdTail {
+  constructor() {
+    this.files = [];
+    this.currentTabIndex = 0;
+  }
+
+  parseArguments(args) {
+    const helpFlags = ['-h', '--help'];
+    
+    if (args.some(arg => helpFlags.includes(arg))) {
+      return { showHelp: true };
+    }
+
+    return { showHelp: false };
+  }
+
+  expandFiles(args, currentDir = process.cwd()) {
+    const files = [];
+    
+    if (args.length === 0) {
+      // Default to TODO.md in current directory
+      const defaultFile = path.join(currentDir, 'TODO.md');
+      if (fs.existsSync(defaultFile)) {
+        files.push(defaultFile);
+      }
+    } else {
+      args.forEach(arg => {
+        if (arg.includes('*')) {
+          // Handle wildcards
+          const mdFiles = fs.readdirSync(currentDir)
+            .filter(file => file.endsWith('.md'))
+            .sort()
+            .map(f => path.resolve(currentDir, f));
+          files.push(...mdFiles);
+        } else {
+          // Resolve individual file paths
+          const filePath = path.resolve(currentDir, arg);
+          if (fs.existsSync(filePath) && filePath.endsWith('.md')) {
+            files.push(filePath);
+          }
+        }
+      });
+    }
+
+    // Remove duplicates
+    return [...new Set(files)];
+  }
+
+  validateFiles(files) {
+    if (!Array.isArray(files) || files.length === 0) {
+      throw new Error('No markdown files found to watch');
+    }
+    return true;
+  }
+
+  renderTabs(files, currentIndex, width = 80) {
+    if (files.length <= 1) return '';
+    
+    const tabs = files.map((file, index) => {
+      const filename = path.basename(file);
+      const isActive = index === currentIndex;
+      
+      if (isActive) {
+        return `[${filename}]`;
+      } else {
+        return ` ${filename} `;
+      }
+    });
+    
+    const tabLine = tabs.join(' │ ');
+    return `${tabLine}\n${'─'.repeat(width)}\n`;
+  }
+
+  formatContent(content, filename, width = 80) {
+    const lines = [];
+    lines.push('\n' + '═'.repeat(width));
+    lines.push(filename.toUpperCase());
+    lines.push('═'.repeat(width) + '\n');
+    lines.push(content);
+    lines.push('\n' + '═'.repeat(width));
+    return lines.join('\n');
+  }
+
+  getHelpText() {
+    return `
+mdtail - Terminal markdown viewer with live refresh
+
+Usage:
+  mdtail [file1.md] [file2.md] ...  Watch specific markdown files
+  mdtail                             Watch TODO.md (default)
+  mdtail -h, --help                  Show this help message
+
+Navigation:
+  ← / → Arrow Keys                   Switch between tabs
+  Ctrl+C                             Exit
+
+Examples:
+  mdtail README.md                   Watch README.md
+  mdtail todo.md notes.md            Watch multiple files with tabs
+  mdtail *.md                        Watch all markdown files in tabs
+`;
+  }
+
+  navigateTab(direction) {
+    if (this.files.length <= 1) return false;
+    
+    if (direction === 'left') {
+      this.currentTabIndex = (this.currentTabIndex - 1 + this.files.length) % this.files.length;
+    } else if (direction === 'right') {
+      this.currentTabIndex = (this.currentTabIndex + 1) % this.files.length;
+    } else {
+      return false;
+    }
+    
+    return true;
+  }
+}
+
+module.exports = MdTail;