navegator/dev/issues/014-network-mocking-avanzado.md

Issue #014: Network Mocking Avanzado

Tipo: Enhancement Prioridad: Baja (Avanzado) Estado: Pendiente

Descripción

Implementar sistema avanzado de interceptación y mocking de requests HTTP/HTTPS.

Funcionalidad deseada

• Interceptar requests antes de enviar
• Modificar request (URL, headers, body, method)
• Mock responses completas
• Simular latencia de red
• Simular errores de red
• Registro de todas las requests
• Pattern matching avanzado (regex, wildcards)
• Condicional (solo interceptar si...)

API propuesta

type MockResponse struct {
    Status  int
    Headers map[string]string
    Body    string
    Delay   time.Duration
}

type InterceptorFunc func(req *Request) (*MockResponse, error)

type RequestPattern struct {
    URL       string // Glob o regex
    Method    string // GET, POST, etc.
    Condition func(*Request) bool
}

func (b *Browser) InterceptRequest(ctx context.Context, pattern RequestPattern, handler InterceptorFunc) error
func (b *Browser) MockResponse(ctx context.Context, pattern string, response *MockResponse) error
func (b *Browser) AbortRequest(ctx context.Context, pattern string) error
func (b *Browser) SimulateOffline(ctx context.Context) error
func (b *Browser) SimulateSlowConnection(ctx context.Context, downloadThroughput, uploadThroughput int) error
func (b *Browser) GetAllRequests(ctx context.Context) ([]*Request, error)

Uso

Mock API response

b.MockResponse(ctx, "**/api/users", &browser.MockResponse{
    Status: 200,
    Headers: map[string]string{
        "Content-Type": "application/json",
    },
    Body: `{"users": [{"id": 1, "name": "Test"}]}`,
    Delay: 100 * time.Millisecond,
})

Interceptar y modificar

b.InterceptRequest(ctx, browser.RequestPattern{
    URL: "**/api/**",
}, func(req *browser.Request) (*browser.MockResponse, error) {
    // Modificar headers
    req.Headers["Authorization"] = "Bearer fake-token"

    // Dejar continuar request (nil = no mockear)
    return nil, nil
})

Simular error de red

b.AbortRequest(ctx, "**/slow-endpoint")

Simular conexión lenta

b.SimulateSlowConnection(ctx,
    500*1024,  // 500 KB/s download
    100*1024,  // 100 KB/s upload
)

Capturar todas las requests

requests, _ := b.GetAllRequests(ctx)
for _, req := range requests {
    log.Printf("%s %s - %d", req.Method, req.URL, req.StatusCode)
}

CDP Methods

• Fetch.enable - Habilitar interceptación
• Fetch.requestPaused - Request interceptado
• Fetch.continueRequest - Continuar con cambios
• Fetch.fulfillRequest - Mock response
• Fetch.failRequest - Abortar request
• Network.emulateNetworkConditions - Simular latencia

Referencias

• CDP Fetch: https://chromedevtools.github.io/devtools-protocol/tot/Fetch/
• Playwright route: https://playwright.dev/docs/network
• Puppeteer interception: https://pptr.dev/guides/request-interception