[Feature]: Add Decorator-Based API Testing Support for Enhanced

[json-choi]

Current Situation/Problem

Currently, itdoc provides excellent test-driven API documentation generation through its function-based approach using describeAPI() and itDoc(). However, this approach requires developers to write verbose boilerplate code and manually integrate with test frameworks

Proposed Feature

Introduce decorator-based API documentation support that allows developers to add documentation decorators to existing E2E tests in their preferred test frameworks, providing a seamless way to generate API documentation from existing test suites:

// Proposed decorator-based approach - enhancing existing E2E tests
import { ApiDoc, DocumentEndpoint } from 'itdoc/decorators'
import request from 'supertest'
import { app } from '../src/app'

describe('User Authentication API', () => {
    
    @ApiDoc({
        method: "POST",
        path: "/signup",
        summary: "User Registration API",
        description: "Register a new user with username and password",
        tag: "Auth"
    })
    it('should register user successfully', async () => {
        const response = await request(app)
            .post('/signup')
            .send({
                username: 'testuser',
                password: 'password123'
            })
            .expect(201)
        
        expect(response.body).toEqual({
            message: 'User registered successfully',
            userId: expect.any(String)
        })
    })

    @ApiDoc({
        method: "POST",
        path: "/signup",
        summary: "User Registration API - Validation Error",
        description: "Returns error when username is missing",
        tag: "Auth"
    })
    it('should fail when username is missing', async () => {
        const response = await request(app)
            .post('/signup')
            .send({
                password: 'password123'
            })
            .expect(400)
        
        expect(response.body).toEqual({
            error: 'Username is required'
        })
    })
})

// Works with any test framework
describe('Product API', () => {
    
    @DocumentEndpoint({
        method: "GET",
        path: "/products/:id",
        summary: "Get Product by ID",
        tag: "Products"
    })
    test('should return product details', async () => {
        // Existing Jest/Mocha/Vitest test code
        const response = await request(app)
            .get('/products/123')
            .expect(200)
        
        expect(response.body.id).toBe(123)
        expect(response.body.name).toBeDefined()
    })
})

Benefits of decorator-based approach:

1. Non-intrusive integration: Add documentation to existing E2E tests without changing test logic
2. Framework agnostic: Works seamlessly with any test framework (Jest, Mocha, Vitest, etc.)
3. Minimal learning curve: Developers can keep using their familiar testing patterns
4. Better IDE support: Enhanced autocomplete, IntelliSense, and refactoring capabilities
5. Gradual adoption: Teams can incrementally add documentation decorators to existing tests
6. Automatic documentation generation: Extract API specs directly from real, working tests
7. Test-driven documentation: Documentation is always in sync with actual test behavior

Alternatives (Optional)

No response

Additional Information

No response