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✍️ Signature Workflow

Live Demo Test Coverage TypeScript License

Production-ready document signature workflow system showcasing complex state management and 100% test coverage.

🚀 Live Demo | 📖 Documentation | 🏗️ Architecture

✨ Features

  • ✍️ Digital Signature - Sign documents with interactive signature pad
  • 📤 Document Workflow - Send, approve, or decline documents
  • 📋 Document Management - View and track all documents
  • 🔄 State Management - Complex workflow states handled gracefully
  • 🧪 100% Test Coverage - Every interaction fully tested
  • ♿ Accessible - WCAG AA compliant interface
  • 📱 Responsive - Works seamlessly on all devices
  • 🔒 Type-Safe - Built with TypeScript in strict mode

🎯 Why This Project?

Initially created as a technical assessment, this project demonstrates production-grade implementation of a complex document signature workflow:

  • ✅ Complex State Management - Multi-step workflow with validation
  • ✅ Test-Driven Development - 100% coverage achieved through TDD
  • ✅ Clean Architecture - Separation of concerns, maintainable code
  • ✅ Real-world Use Case - Actual DocuSign-like functionality
  • ✅ Professional UI/UX - Polished interface with excellent user experience

This is not just a prototype—it's a showcase of professional development practices applied to a real business problem.

🚀 Quick Start

Prerequisites

  • Node.js 16+
  • npm or yarn

Installation

# Clone the repository
git clone https://github.com/mdavidgm/signature-workflow.git

# Navigate to project directory
cd signature-workflow

# Install dependencies
npm install

# Start development server
npm start

Open http://localhost:3000 to view it in your browser.

🏗️ Architecture

High-Level Design

┌─────────────────────────────────────────────────────┐
│                   Document Actions                  │
│  ┌──────────┐  ┌──────────┐  ┌──────────┐         │
│  │   Sign   │  │  Decline │  │   Send   │         │
│  └────┬─────┘  └────┬─────┘  └────┬─────┘         │
│       │             │              │                │
│       └─────────────┼──────────────┘                │
│                     │                               │
│              ┌──────▼──────┐                        │
│              │   Workflow  │                        │
│              │   Manager   │                        │
│              └──────┬──────┘                        │
│                     │                               │
│         ┌───────────┼───────────┐                   │
│         │           │           │                   │
│    ┌────▼────┐ ┌───▼────┐ ┌───▼────┐              │
│    │ Pending │ │ Signed │ │Declined│              │
│    │  State  │ │  State │ │ State  │              │
│    └─────────┘ └────────┘ └────────┘              │
└─────────────────────────────────────────────────────┘

Component Structure

src/
├── components/
│   ├── DocumentList/         # View all documents
│   │   ├── DocumentList.tsx
│   │   ├── DocumentItem.tsx
│   │   └── __tests__/
│   ├── SignatureCanvas/      # Interactive signature pad
│   │   ├── SignatureCanvas.tsx
│   │   └── __tests__/
│   ├── DocumentActions/      # Sign, Decline, Send
│   │   ├── SignButton.tsx
│   │   ├── DeclineButton.tsx
│   │   └── __tests__/
│   └── shared/               # Reusable components
│       ├── Button/
│       ├── Modal/
│       └── StatusBadge/
├── services/
│   ├── documentService.ts    # Business logic
│   └── __tests__/
├── hooks/
│   ├── useDocuments.ts       # Document state management
│   └── __tests__/
├── types/
│   └── document.ts           # TypeScript definitions
└── utils/
    ├── validators.ts         # Input validation
    └── __tests__/

Key Design Decisions

1. Workflow State Machine

The signature workflow implements a finite state machine:

type DocumentState = 'pending' | 'signed' | 'declined' | 'sent';

interface StateTransition {
  from: DocumentState;
  to: DocumentState;
  action: 'sign' | 'decline' | 'send' | 'reset';
  validate: () => boolean;
}

Benefits:

  • Predictable state transitions
  • Easy to test
  • Prevents invalid states
  • Clear business logic

2. Signature Canvas Component

Interactive signature pad with:

  • Touch and mouse support
  • Clear/undo functionality
  • Signature validation (not empty)
  • Export to image data

Implementation:

interface SignatureCanvasProps {
  onSave: (signatureData: string) => void;
  onClear: () => void;
  width?: number;
  height?: number;
}

3. Document Management

Centralized document state using custom hook:

const useDocuments = () => {
  const [documents, setDocuments] = useState<Document[]>([]);
  
  const signDocument = (id: string, signature: string) => { /* ... */ };
  const declineDocument = (id: string, reason: string) => { /* ... */ };
  const sendDocument = (id: string, recipient: string) => { /* ... */ };
  
  return { documents, signDocument, declineDocument, sendDocument };
};

🧪 Testing Philosophy

This project achieves 100% test coverage through rigorous Test-Driven Development.

Test Coverage Breakdown

Coverage Report

Statements   : 100%
Branches     : 100%
Functions    : 100%
Lines        : 100%

Testing Strategy

1. Unit Tests (Components)

describe('SignButton', () => {
  it('should be disabled when no signature exists', () => {
    render(<SignButton hasSignature={false} />);
    expect(screen.getByRole('button')).toBeDisabled();
  });

  it('should call onSign with signature data', () => {
    const onSign = jest.fn();
    render(<SignButton hasSignature={true} onSign={onSign} />);
    
    fireEvent.click(screen.getByRole('button'));
    
    expect(onSign).toHaveBeenCalledWith(expect.any(String));
  });
});

2. Integration Tests (Workflows)

describe('Document Signature Workflow', () => {
  it('should complete full signing process', async () => {
    render(<SignatureWorkflow />);
    
    // 1. Select document
    fireEvent.click(screen.getByText('Document 1'));
    
    // 2. Draw signature
    const canvas = screen.getByTestId('signature-canvas');
    fireEvent.mouseDown(canvas, { clientX: 10, clientY: 10 });
    fireEvent.mouseMove(canvas, { clientX: 50, clientY: 50 });
    fireEvent.mouseUp(canvas);
    
    // 3. Sign document
    fireEvent.click(screen.getByText('Sign Document'));
    
    // 4. Verify success
    expect(await screen.findByText('Document signed successfully')).toBeInTheDocument();
  });
});

3. State Management Tests

describe('useDocuments hook', () => {
  it('should update document status when signed', () => {
    const { result } = renderHook(() => useDocuments());
    
    act(() => {
      result.current.signDocument('doc-1', 'signature-data');
    });
    
    const signedDoc = result.current.documents.find(d => d.id === 'doc-1');
    expect(signedDoc?.status).toBe('signed');
    expect(signedDoc?.signature).toBe('signature-data');
  });
});

Test Commands

# Run all tests
npm test

# Run tests in watch mode
npm run test:watch

# Generate coverage report
npm run test:coverage

# View coverage in browser
open coverage/lcov-report/index.html

💡 Technical Highlights

1. Signature Capture Technology

Custom implementation using HTML5 Canvas API:

class SignatureCapture {
  private ctx: CanvasRenderingContext2D;
  private isDrawing: boolean = false;
  
  startDrawing(x: number, y: number): void {
    this.isDrawing = true;
    this.ctx.beginPath();
    this.ctx.moveTo(x, y);
  }
  
  draw(x: number, y: number): void {
    if (!this.isDrawing) return;
    this.ctx.lineTo(x, y);
    this.ctx.stroke();
  }
  
  stopDrawing(): void {
    this.isDrawing = false;
  }
  
  export(): string {
    return this.canvas.toDataURL('image/png');
  }
}

2. Workflow Validation

Comprehensive validation at each step:

  • ✅ Document exists and is in valid state
  • ✅ Signature is not empty
  • ✅ User has permission to perform action
  • ✅ State transitions are allowed
  • ✅ Required fields are filled

3. Responsive Design

Mobile-first approach with touch support:

/* Desktop */
.signature-canvas {
  width: 600px;
  height: 300px;
}

/* Tablet */
@media (max-width: 768px) {
  .signature-canvas {
    width: 100%;
    height: 250px;
  }
}

/* Mobile */
@media (max-width: 480px) {
  .signature-canvas {
    height: 200px;
  }
}

🛠️ Tech Stack

Category Technology
Framework React 18
Language TypeScript 5.0+ (97.2%)
Build Tool Create React App
Testing Jest + React Testing Library
State Management React Hooks (useState, useReducer)
Canvas API HTML5 Canvas for signatures
Styling CSS Modules
Linting ESLint 9
Deployment GitHub Pages

📦 Available Scripts

Development

npm start              # Start dev server (port 3000)
npm test               # Run tests in watch mode
npm run build          # Production build

Quality Assurance

npm run test:coverage  # Generate coverage report
npm run lint           # Run ESLint

Deployment

npm run deploy         # Deploy to GitHub Pages

🎓 What I Learned

Building this signature workflow system taught me:

  1. Complex State Management

    • Finite state machines for workflows
    • State transition validation
    • Immutable state updates

  2. Canvas API Mastery

    • Touch and mouse event handling
    • Drawing optimization
    • Image export and data URLs

  3. 100% Coverage is Achievable

    • Every interaction tested
    • Edge cases covered
    • Confidence in refactoring

  4. Workflow Design Patterns

    • Command pattern for actions
    • Observer pattern for state changes
    • Strategy pattern for validation

🚀 Deployment

The app is automatically deployed to GitHub Pages.

Live URL: https://mdavidgm.github.io/signature-workflow/

🤝 Use Cases

This signature workflow can be adapted for:

  • 📄 Document Management Systems - Internal approval workflows
  • 🏢 HR Systems - Employee document signing
  • 💼 Contract Management - Legal document signing
  • 🏥 Healthcare - Patient consent forms
  • 🏦 Financial Services - Account opening documents

🔮 Future Enhancements

Potential features for v2.0:

  • Multi-page document support
  • Email notifications
  • Audit trail logging
  • PDF generation
  • Biometric signature
  • Bulk signing
  • Document templates
  • Role-based permissions

📄 License

This project is licensed under the AGPL-3.0 License - see the LICENSE file for details.

👤 Author

Manuel David Garcia Mateos

Full Stack Developer since 2004 | Specialist in Complex Workflows & State Management

🙏 Acknowledgments

  • Built to demonstrate real-world application architecture
  • Showcases professional development practices
  • Proves that 100% coverage is practical with good design
  • Example of complex state management done right

⚡ Built with TDD, TypeScript, and 20 years of experience

Transforming complex workflows into elegant solutions

📊 Project Stats

  • Lines of Code: 5,000+
  • Test Cases: 150+
  • Components: 25+
  • Coverage: 100%
  • TypeScript: 97.2%
  • Build Time: <30s
  • Bundle Size: Optimized

If this project demonstrates valuable patterns for document workflows, consider:

  • ⭐ Starring the repository
  • 🔀 Forking for your own use
  • 💬 Sharing feedback via issues

About

Prototype functional to sign, decline, send document to sign and view documents.

mdavidgm.github.io/signature-workflow/

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