feat: implement advanced test provider with interactive UI and multiple scenarios

- Add comprehensive test provider with configurable payment outcomes (paid, failed, cancelled, expired, pending)
- Support multiple payment methods (iDEAL, Credit Card, PayPal, Apple Pay, Bank Transfer)
- Interactive test payment UI with responsive design and real-time processing simulation
- Test mode indicators including warning banners, badges, and console warnings
- React components for admin UI integration (TestModeWarningBanner, TestModeBadge, TestPaymentControls)
- API endpoints for test payment processing and status polling
- Configurable scenarios with custom delays and outcomes
- Production safety mechanisms and clear test mode indicators
- Complete documentation and usage examples

Implements GitHub issue #20 for advanced test provider functionality.

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

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

docs/test-provider-example.md

@@ -0,0 +1,147 @@
+# Advanced Test Provider Example
+
+The advanced test provider allows you to test complex payment scenarios with an interactive UI for development purposes.
+
+## Basic Configuration
+
+```typescript
+import { billingPlugin, testProvider } from '@xtr-dev/payload-billing'
+
+// Configure the test provider
+const testProviderConfig = {
+  enabled: true, // Enable the test provider
+  defaultDelay: 2000, // Default delay in milliseconds
+  baseUrl: process.env.PAYLOAD_PUBLIC_SERVER_URL || 'http://localhost:3000',
+  customUiRoute: '/test-payment', // Custom route for test payment UI
+  testModeIndicators: {
+    showWarningBanners: true, // Show warning banners in test mode
+    showTestBadges: true, // Show test badges
+    consoleWarnings: true, // Show console warnings
+  }
+}
+
+// Add to your payload config
+export default buildConfig({
+  plugins: [
+    billingPlugin({
+      providers: [
+        testProvider(testProviderConfig)
+      ]
+    })
+  ]
+})
+```
+
+## Custom Scenarios
+
+You can define custom payment scenarios:
+
+```typescript
+const customScenarios = [
+  {
+    id: 'quick-success',
+    name: 'Quick Success',
+    description: 'Payment succeeds in 1 second',
+    outcome: 'paid' as const,
+    delay: 1000,
+    method: 'creditcard' as const
+  },
+  {
+    id: 'network-timeout',
+    name: 'Network Timeout',
+    description: 'Simulates network timeout',
+    outcome: 'failed' as const,
+    delay: 10000
+  },
+  {
+    id: 'user-abandonment',
+    name: 'User Abandonment',
+    description: 'User closes payment window',
+    outcome: 'cancelled' as const,
+    delay: 5000
+  }
+]
+
+const testProviderConfig = {
+  enabled: true,
+  scenarios: customScenarios,
+  // ... other config
+}
+```
+
+## Available Payment Outcomes
+
+- `paid` - Payment succeeds
+- `failed` - Payment fails
+- `cancelled` - Payment is cancelled by user
+- `expired` - Payment expires
+- `pending` - Payment remains pending
+
+## Available Payment Methods
+
+- `ideal` - iDEAL (Dutch banking)
+- `creditcard` - Credit/Debit Cards
+- `paypal` - PayPal
+- `applepay` - Apple Pay
+- `banktransfer` - Bank Transfer
+
+## Using the Test UI
+
+1. Create a payment using the test provider
+2. The payment will return a `paymentUrl` in the provider data
+3. Navigate to this URL to access the interactive test interface
+4. Select a payment method and scenario
+5. Click "Process Test Payment" to simulate the payment
+6. The payment status will update automatically based on the selected scenario
+
+## React Components
+
+Use the provided React components in your admin interface:
+
+```tsx
+import { TestModeWarningBanner, TestModeBadge, TestPaymentControls } from '@xtr-dev/payload-billing/client'
+
+// Show warning banner when in test mode
+<TestModeWarningBanner visible={isTestMode} />
+
+// Add test badge to payment status
+<div>
+  Payment Status: {status}
+  <TestModeBadge visible={isTestMode} />
+</div>
+
+// Payment testing controls
+<TestPaymentControls
+  paymentId={paymentId}
+  onScenarioSelect={(scenario) => console.log('Selected scenario:', scenario)}
+  onMethodSelect={(method) => console.log('Selected method:', method)}
+/>
+```
+
+## API Endpoints
+
+The test provider automatically registers these endpoints:
+
+- `GET /api/payload-billing/test/payment/:id` - Test payment UI
+- `POST /api/payload-billing/test/process` - Process test payment
+- `GET /api/payload-billing/test/status/:id` - Get payment status
+
+## Development Tips
+
+1. **Console Warnings**: Keep `consoleWarnings: true` to get notifications about test mode
+2. **Visual Indicators**: Use warning banners and badges to clearly mark test payments
+3. **Custom Scenarios**: Create scenarios that match your specific use cases
+4. **Automated Testing**: Use the test provider in your e2e tests for predictable payment outcomes
+5. **Method Testing**: Test different payment methods to ensure your UI handles them correctly
+
+## Production Safety
+
+The test provider includes several safety mechanisms:
+
+- Must be explicitly enabled with `enabled: true`
+- Clearly marked with test indicators
+- Console warnings when active
+- Separate endpoint namespace (`/payload-billing/test/`)
+- No real payment processing
+
+**Important**: Never use the test provider in production environments!

src/exports/client.tsx

@@ -60,9 +60,130 @@ export const PaymentStatusBadge: React.FC<{ status: string }> = ({ status }) =>
   )
 }
 
+// Test mode indicator components
+export const TestModeWarningBanner: React.FC<{ visible?: boolean }> = ({ visible = true }) => {
+  if (!visible) return null
+
+  return (
+    <div style={{
+      background: 'linear-gradient(90deg, #ff6b6b, #ffa726)',
+      color: 'white',
+      padding: '12px 20px',
+      textAlign: 'center',
+      fontWeight: 600,
+      fontSize: '14px',
+      marginBottom: '20px',
+      borderRadius: '4px'
+    }}>
+      🧪 TEST MODE - Payment system is running in test mode for development
+    </div>
+  )
+}
+
+export const TestModeBadge: React.FC<{ visible?: boolean }> = ({ visible = true }) => {
+  if (!visible) return null
+
+  return (
+    <span style={{
+      display: 'inline-block',
+      background: '#6c757d',
+      color: 'white',
+      padding: '4px 8px',
+      borderRadius: '4px',
+      fontSize: '12px',
+      fontWeight: 600,
+      textTransform: 'uppercase',
+      marginLeft: '8px'
+    }}>
+      Test
+    </span>
+  )
+}
+
+export const TestPaymentControls: React.FC<{
+  paymentId?: string
+  onScenarioSelect?: (scenario: string) => void
+  onMethodSelect?: (method: string) => void
+}> = ({ paymentId, onScenarioSelect, onMethodSelect }) => {
+  const [selectedScenario, setSelectedScenario] = React.useState('')
+  const [selectedMethod, setSelectedMethod] = React.useState('')
+
+  const scenarios = [
+    { id: 'instant-success', name: 'Instant Success', description: 'Payment succeeds immediately' },
+    { id: 'delayed-success', name: 'Delayed Success', description: 'Payment succeeds after delay' },
+    { id: 'cancelled-payment', name: 'Cancelled Payment', description: 'User cancels payment' },
+    { id: 'declined-payment', name: 'Declined Payment', description: 'Payment declined' },
+    { id: 'expired-payment', name: 'Expired Payment', description: 'Payment expires' },
+    { id: 'pending-payment', name: 'Pending Payment', description: 'Payment stays pending' }
+  ]
+
+  const methods = [
+    { id: 'ideal', name: 'iDEAL', icon: '🏦' },
+    { id: 'creditcard', name: 'Credit Card', icon: '💳' },
+    { id: 'paypal', name: 'PayPal', icon: '🅿️' },
+    { id: 'applepay', name: 'Apple Pay', icon: '🍎' },
+    { id: 'banktransfer', name: 'Bank Transfer', icon: '🏛️' }
+  ]
+
+  return (
+    <div style={{ border: '1px solid #e9ecef', borderRadius: '8px', padding: '16px', margin: '16px 0' }}>
+      <h4 style={{ marginBottom: '12px', color: '#2c3e50' }}>🧪 Test Payment Controls</h4>
+
+      <div style={{ marginBottom: '16px' }}>
+        <label style={{ display: 'block', marginBottom: '8px', fontWeight: '600' }}>Payment Method:</label>
+        <select
+          value={selectedMethod}
+          onChange={(e) => {
+            setSelectedMethod(e.target.value)
+            onMethodSelect?.(e.target.value)
+          }}
+          style={{ width: '100%', padding: '8px', borderRadius: '4px', border: '1px solid #ccc' }}
+        >
+          <option value="">Select payment method...</option>
+          {methods.map(method => (
+            <option key={method.id} value={method.id}>
+              {method.icon} {method.name}
+            </option>
+          ))}
+        </select>
+      </div>
+
+      <div style={{ marginBottom: '16px' }}>
+        <label style={{ display: 'block', marginBottom: '8px', fontWeight: '600' }}>Test Scenario:</label>
+        <select
+          value={selectedScenario}
+          onChange={(e) => {
+            setSelectedScenario(e.target.value)
+            onScenarioSelect?.(e.target.value)
+          }}
+          style={{ width: '100%', padding: '8px', borderRadius: '4px', border: '1px solid #ccc' }}
+        >
+          <option value="">Select test scenario...</option>
+          {scenarios.map(scenario => (
+            <option key={scenario.id} value={scenario.id}>
+              {scenario.name} - {scenario.description}
+            </option>
+          ))}
+        </select>
+      </div>
+
+      {paymentId && (
+        <div style={{ marginTop: '12px', padding: '8px', background: '#f8f9fa', borderRadius: '4px' }}>
+          <small style={{ color: '#6c757d' }}>
+            Payment ID: <code>{paymentId}</code>
+          </small>
+        </div>
+      )}
+    </div>
+  )
+}
+
 export default {
   BillingDashboardWidget,
   formatCurrency,
   getPaymentStatusColor,
   PaymentStatusBadge,
+  TestModeWarningBanner,
+  TestModeBadge,
+  TestPaymentControls,
 }

src/index.ts

@@ -1,8 +1,17 @@
 
 export { billingPlugin } from './plugin/index.js'
 export { mollieProvider, stripeProvider } from './providers/index.js'
-export type { BillingPluginConfig, CustomerInfoExtractor } from './plugin/config.js'
+export type { BillingPluginConfig, CustomerInfoExtractor, AdvancedTestProviderConfig } from './plugin/config.js'
 export type { Invoice, Payment, Refund } from './plugin/types/index.js'
 export type { PaymentProvider, ProviderData } from './providers/types.js'
-export type { MollieProviderConfig } from './providers/mollie.js'
+
-export type { StripeProviderConfig } from './providers/stripe.js'
+// Export all providers
+export { testProvider } from './providers/test.js'
+export type {
+  StripeProviderConfig,
+  MollieProviderConfig,
+  TestProviderConfig,
+  PaymentOutcome,
+  PaymentMethod,
+  PaymentScenario
+} from './providers/index.js'

src/plugin/config.ts

@@ -19,6 +19,26 @@ export interface TestProviderConfig {
   simulateFailures?: boolean
 }
 
+export interface AdvancedTestProviderConfig {
+  enabled: boolean
+  scenarios?: Array<{
+    id: string
+    name: string
+    description: string
+    outcome: 'paid' | 'failed' | 'cancelled' | 'expired' | 'pending'
+    delay?: number
+    method?: 'ideal' | 'creditcard' | 'paypal' | 'applepay' | 'banktransfer'
+  }>
+  customUiRoute?: string
+  testModeIndicators?: {
+    showWarningBanners?: boolean
+    showTestBadges?: boolean
+    consoleWarnings?: boolean
+  }
+  defaultDelay?: number
+  baseUrl?: string
+}
+
 // Customer info extractor callback type
 export interface CustomerInfoExtractor {
   (customer: any): {

src/providers/index.ts

@@ -1,4 +1,10 @@
 export * from './mollie.js'
 export * from './stripe.js'
+export * from './test.js'
 export * from './types.js'
 export * from './currency.js'
+
+// Re-export provider configurations and types
+export type { StripeProviderConfig } from './stripe.js'
+export type { MollieProviderConfig } from './mollie.js'
+export type { TestProviderConfig, PaymentOutcome, PaymentMethod, PaymentScenario } from './test.js'

src/providers/test.ts

@@ -0,0 +1,719 @@
+import type { Payment } from '../plugin/types/payments.js'
+import type { PaymentProvider, ProviderData } from '../plugin/types/index.js'
+import type { Payload } from 'payload'
+import { webhookResponses, handleWebhookError, logWebhookEvent } from './utils.js'
+import { isValidAmount, isValidCurrencyCode } from './currency.js'
+
+export type PaymentOutcome = 'paid' | 'failed' | 'cancelled' | 'expired' | 'pending'
+
+export type PaymentMethod = 'ideal' | 'creditcard' | 'paypal' | 'applepay' | 'banktransfer'
+
+export interface PaymentScenario {
+  id: string
+  name: string
+  description: string
+  outcome: PaymentOutcome
+  delay?: number // Delay in milliseconds before processing
+  method?: PaymentMethod
+}
+
+export interface TestProviderConfig {
+  enabled: boolean
+  scenarios?: PaymentScenario[]
+  customUiRoute?: string
+  testModeIndicators?: {
+    showWarningBanners?: boolean
+    showTestBadges?: boolean
+    consoleWarnings?: boolean
+  }
+  defaultDelay?: number
+  baseUrl?: string
+}
+
+// Default payment scenarios
+const DEFAULT_SCENARIOS: PaymentScenario[] = [
+  {
+    id: 'instant-success',
+    name: 'Instant Success',
+    description: 'Payment succeeds immediately',
+    outcome: 'paid',
+    delay: 0
+  },
+  {
+    id: 'delayed-success',
+    name: 'Delayed Success',
+    description: 'Payment succeeds after a delay',
+    outcome: 'paid',
+    delay: 3000
+  },
+  {
+    id: 'cancelled-payment',
+    name: 'Cancelled Payment',
+    description: 'User cancels the payment',
+    outcome: 'cancelled',
+    delay: 1000
+  },
+  {
+    id: 'declined-payment',
+    name: 'Declined Payment',
+    description: 'Payment is declined by the provider',
+    outcome: 'failed',
+    delay: 2000
+  },
+  {
+    id: 'expired-payment',
+    name: 'Expired Payment',
+    description: 'Payment expires before completion',
+    outcome: 'expired',
+    delay: 5000
+  },
+  {
+    id: 'pending-payment',
+    name: 'Pending Payment',
+    description: 'Payment remains in pending state',
+    outcome: 'pending',
+    delay: 1500
+  }
+]
+
+// Payment method configurations
+const PAYMENT_METHODS: Record<PaymentMethod, { name: string; icon: string }> = {
+  ideal: { name: 'iDEAL', icon: '🏦' },
+  creditcard: { name: 'Credit Card', icon: '💳' },
+  paypal: { name: 'PayPal', icon: '🅿️' },
+  applepay: { name: 'Apple Pay', icon: '🍎' },
+  banktransfer: { name: 'Bank Transfer', icon: '🏛️' }
+}
+
+// In-memory storage for test payment sessions
+const testPaymentSessions = new Map<string, {
+  id: string
+  payment: Partial<Payment>
+  scenario?: PaymentScenario
+  method?: PaymentMethod
+  createdAt: Date
+  status: PaymentOutcome
+}>()
+
+export const testProvider = (testConfig: TestProviderConfig) => {
+  if (!testConfig.enabled) {
+    throw new Error('Test provider is disabled')
+  }
+
+  const scenarios = testConfig.scenarios || DEFAULT_SCENARIOS
+  const baseUrl = testConfig.baseUrl || (process.env.PAYLOAD_PUBLIC_SERVER_URL || 'http://localhost:3000')
+  const uiRoute = testConfig.customUiRoute || '/test-payment'
+
+  // Log test mode warnings if enabled
+  if (testConfig.testModeIndicators?.consoleWarnings !== false) {
+    console.warn('🧪 [TEST PROVIDER] Payment system is running in test mode')
+  }
+
+  return {
+    key: 'test',
+    onConfig: (config, pluginConfig) => {
+      // Register test payment UI endpoint
+      config.endpoints = [
+        ...(config.endpoints || []),
+        {
+          path: '/payload-billing/test/payment/:id',
+          method: 'get',
+          handler: async (req) => {
+            // Extract payment ID from URL path
+            const urlParts = req.url?.split('/') || []
+            const paymentId = urlParts[urlParts.length - 1]
+            if (!paymentId) {
+              return new Response('Payment ID required', { status: 400 })
+            }
+
+            const session = testPaymentSessions.get(paymentId)
+            if (!session) {
+              return new Response('Payment session not found', { status: 404 })
+            }
+
+            // Generate test payment UI
+            const html = generateTestPaymentUI(session, scenarios, uiRoute, baseUrl, testConfig)
+            return new Response(html, {
+              headers: { 'Content-Type': 'text/html' }
+            })
+          }
+        },
+        {
+          path: '/payload-billing/test/process',
+          method: 'post',
+          handler: async (req) => {
+            try {
+              const payload = req.payload
+              const body = await req.json?.() || {}
+              const { paymentId, scenarioId, method } = body as any
+
+              const session = testPaymentSessions.get(paymentId)
+              if (!session) {
+                return new Response(JSON.stringify({ error: 'Payment session not found' }), {
+                  status: 404,
+                  headers: { 'Content-Type': 'application/json' }
+                })
+              }
+
+              const scenario = scenarios.find(s => s.id === scenarioId)
+              if (!scenario) {
+                return new Response(JSON.stringify({ error: 'Invalid scenario' }), {
+                  status: 400,
+                  headers: { 'Content-Type': 'application/json' }
+                })
+              }
+
+              // Update session with selected scenario and method
+              session.scenario = scenario
+              session.method = method
+              session.status = 'pending'
+
+              // Process payment after delay
+              setTimeout(async () => {
+                await processTestPayment(payload, session, pluginConfig)
+              }, scenario.delay || testConfig.defaultDelay || 1000)
+
+              return new Response(JSON.stringify({
+                success: true,
+                status: 'processing',
+                scenario: scenario.name,
+                delay: scenario.delay || testConfig.defaultDelay || 1000
+              }), {
+                headers: { 'Content-Type': 'application/json' }
+              })
+            } catch (error) {
+              return handleWebhookError('Test Provider', error, 'Failed to process test payment')
+            }
+          }
+        },
+        {
+          path: '/payload-billing/test/status/:id',
+          method: 'get',
+          handler: async (req) => {
+            // Extract payment ID from URL path
+            const urlParts = req.url?.split('/') || []
+            const paymentId = urlParts[urlParts.length - 1]
+            if (!paymentId) {
+              return new Response(JSON.stringify({ error: 'Payment ID required' }), {
+                status: 400,
+                headers: { 'Content-Type': 'application/json' }
+              })
+            }
+
+            const session = testPaymentSessions.get(paymentId)
+            if (!session) {
+              return new Response(JSON.stringify({ error: 'Payment session not found' }), {
+                status: 404,
+                headers: { 'Content-Type': 'application/json' }
+              })
+            }
+
+            return new Response(JSON.stringify({
+              status: session.status,
+              scenario: session.scenario?.name,
+              method: session.method ? PAYMENT_METHODS[session.method]?.name : undefined
+            }), {
+              headers: { 'Content-Type': 'application/json' }
+            })
+          }
+        }
+      ]
+    },
+    onInit: async (payload: Payload) => {
+      logWebhookEvent('Test Provider', 'Test payment provider initialized')
+
+      // Clean up old sessions periodically (older than 1 hour)
+      setInterval(() => {
+        const oneHourAgo = new Date(Date.now() - 60 * 60 * 1000)
+        testPaymentSessions.forEach((session, id) => {
+          if (session.createdAt < oneHourAgo) {
+            testPaymentSessions.delete(id)
+          }
+        })
+      }, 10 * 60 * 1000) // Clean every 10 minutes
+    },
+    initPayment: async (payload, payment) => {
+      // Validate required fields
+      if (!payment.amount) {
+        throw new Error('Amount is required')
+      }
+      if (!payment.currency) {
+        throw new Error('Currency is required')
+      }
+
+      // Validate amount
+      if (!isValidAmount(payment.amount)) {
+        throw new Error('Invalid amount: must be a positive integer within reasonable limits')
+      }
+
+      // Validate currency code
+      if (!isValidCurrencyCode(payment.currency)) {
+        throw new Error('Invalid currency: must be a 3-letter ISO code')
+      }
+
+      // Generate unique test payment ID
+      const testPaymentId = `test_pay_${Date.now()}_${Math.random().toString(36).substr(2, 9)}`
+
+      // Create test payment session
+      const session = {
+        id: testPaymentId,
+        payment: { ...payment },
+        createdAt: new Date(),
+        status: 'pending' as PaymentOutcome
+      }
+
+      testPaymentSessions.set(testPaymentId, session)
+
+      // Set provider ID and data
+      payment.providerId = testPaymentId
+      const providerData: ProviderData = {
+        raw: {
+          id: testPaymentId,
+          amount: payment.amount,
+          currency: payment.currency,
+          description: payment.description,
+          status: 'pending',
+          testMode: true,
+          paymentUrl: `${baseUrl}/api/payload-billing/test/payment/${testPaymentId}`,
+          scenarios: scenarios.map(s => ({ id: s.id, name: s.name, description: s.description })),
+          methods: Object.entries(PAYMENT_METHODS).map(([key, value]) => ({
+            id: key,
+            name: value.name,
+            icon: value.icon
+          }))
+        },
+        timestamp: new Date().toISOString(),
+        provider: 'test'
+      }
+      payment.providerData = providerData
+
+      return payment
+    },
+  } satisfies PaymentProvider
+}
+
+// Helper function to process test payment based on scenario
+async function processTestPayment(
+  payload: Payload,
+  session: any,
+  pluginConfig: any
+) {
+  try {
+    if (!session.scenario) return
+
+    // Map scenario outcome to payment status
+    let finalStatus: Payment['status'] = 'pending'
+    switch (session.scenario.outcome) {
+      case 'paid':
+        finalStatus = 'succeeded'
+        break
+      case 'failed':
+        finalStatus = 'failed'
+        break
+      case 'cancelled':
+        finalStatus = 'canceled'
+        break
+      case 'expired':
+        finalStatus = 'canceled' // Treat expired as canceled
+        break
+      case 'pending':
+        finalStatus = 'pending'
+        break
+    }
+
+    // Update session status
+    session.status = session.scenario.outcome
+
+    // Find and update the payment in the database
+    const paymentsCollection = pluginConfig.collections?.payments || 'payments'
+    const payments = await payload.find({
+      collection: paymentsCollection,
+      where: {
+        providerId: {
+          equals: session.id
+        }
+      },
+      limit: 1
+    })
+
+    if (payments.docs.length > 0) {
+      const payment = payments.docs[0]
+
+      // Update payment with final status and provider data
+      const updatedProviderData: ProviderData = {
+        raw: {
+          ...session.payment,
+          id: session.id,
+          status: session.scenario.outcome,
+          scenario: session.scenario.name,
+          method: session.method,
+          processedAt: new Date().toISOString(),
+          testMode: true
+        },
+        timestamp: new Date().toISOString(),
+        provider: 'test'
+      }
+
+      await payload.update({
+        collection: paymentsCollection,
+        id: payment.id,
+        data: {
+          status: finalStatus,
+          providerData: updatedProviderData
+        }
+      })
+
+      logWebhookEvent('Test Provider', `Payment ${session.id} processed with outcome: ${session.scenario.outcome}`)
+    }
+  } catch (error) {
+    console.error('[Test Provider] Failed to process payment:', error)
+    session.status = 'failed'
+  }
+}
+
+// Helper function to generate test payment UI
+function generateTestPaymentUI(
+  session: any,
+  scenarios: PaymentScenario[],
+  uiRoute: string,
+  baseUrl: string,
+  testConfig: TestProviderConfig
+): string {
+  const payment = session.payment
+  const testModeIndicators = testConfig.testModeIndicators || {}
+
+  return `<!DOCTYPE html>
+<html lang="en">
+<head>
+    <meta charset="UTF-8">
+    <meta name="viewport" content="width=device-width, initial-scale=1.0">
+    <title>Test Payment - ${payment.description || 'Payment'}</title>
+    <style>
+        * { box-sizing: border-box; margin: 0; padding: 0; }
+        body {
+            font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
+            background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
+            min-height: 100vh;
+            padding: 20px;
+        }
+        .container {
+            max-width: 600px;
+            margin: 0 auto;
+            background: white;
+            border-radius: 12px;
+            box-shadow: 0 20px 40px rgba(0,0,0,0.1);
+            overflow: hidden;
+        }
+        ${testModeIndicators.showWarningBanners !== false ? `
+        .test-banner {
+            background: linear-gradient(90deg, #ff6b6b, #ffa726);
+            color: white;
+            padding: 12px 20px;
+            text-align: center;
+            font-weight: 600;
+            font-size: 14px;
+        }
+        ` : ''}
+        .header {
+            background: #f8f9fa;
+            padding: 30px 40px 20px;
+            border-bottom: 1px solid #e9ecef;
+        }
+        .title {
+            font-size: 24px;
+            font-weight: 700;
+            color: #2c3e50;
+            margin-bottom: 8px;
+        }
+        .amount {
+            font-size: 32px;
+            font-weight: 800;
+            color: #27ae60;
+            margin-bottom: 16px;
+        }
+        .description {
+            color: #6c757d;
+            font-size: 16px;
+            line-height: 1.5;
+        }
+        .content { padding: 40px; }
+        .section { margin-bottom: 30px; }
+        .section-title {
+            font-size: 18px;
+            font-weight: 600;
+            color: #2c3e50;
+            margin-bottom: 16px;
+            display: flex;
+            align-items: center;
+            gap: 8px;
+        }
+        .payment-methods {
+            display: grid;
+            grid-template-columns: repeat(auto-fit, minmax(120px, 1fr));
+            gap: 12px;
+            margin-bottom: 20px;
+        }
+        .method {
+            border: 2px solid #e9ecef;
+            border-radius: 8px;
+            padding: 16px 12px;
+            text-align: center;
+            cursor: pointer;
+            transition: all 0.2s;
+            background: white;
+        }
+        .method:hover {
+            border-color: #007bff;
+            background: #f8f9ff;
+        }
+        .method.selected {
+            border-color: #007bff;
+            background: #007bff;
+            color: white;
+        }
+        .method-icon { font-size: 24px; margin-bottom: 8px; }
+        .method-name { font-size: 12px; font-weight: 500; }
+        .scenarios {
+            display: grid;
+            gap: 12px;
+            margin-bottom: 20px;
+        }
+        .scenario {
+            border: 2px solid #e9ecef;
+            border-radius: 8px;
+            padding: 16px;
+            cursor: pointer;
+            transition: all 0.2s;
+            background: white;
+        }
+        .scenario:hover {
+            border-color: #28a745;
+            background: #f8fff9;
+        }
+        .scenario.selected {
+            border-color: #28a745;
+            background: #28a745;
+            color: white;
+        }
+        .scenario-name { font-weight: 600; margin-bottom: 4px; }
+        .scenario-desc { font-size: 14px; opacity: 0.8; }
+        .process-btn {
+            width: 100%;
+            background: linear-gradient(135deg, #007bff, #0056b3);
+            color: white;
+            border: none;
+            padding: 16px;
+            border-radius: 8px;
+            font-size: 16px;
+            font-weight: 600;
+            cursor: pointer;
+            transition: all 0.2s;
+            margin-top: 20px;
+        }
+        .process-btn:hover:not(:disabled) {
+            transform: translateY(-2px);
+            box-shadow: 0 8px 20px rgba(0,123,255,0.3);
+        }
+        .process-btn:disabled {
+            opacity: 0.6;
+            cursor: not-allowed;
+            transform: none;
+        }
+        .status {
+            text-align: center;
+            padding: 20px;
+            border-radius: 8px;
+            margin-top: 20px;
+            font-weight: 600;
+        }
+        .status.processing { background: #fff3cd; color: #856404; }
+        .status.success { background: #d4edda; color: #155724; }
+        .status.error { background: #f8d7da; color: #721c24; }
+        .loading {
+            display: inline-block;
+            width: 20px;
+            height: 20px;
+            border: 3px solid #f3f3f3;
+            border-top: 3px solid #007bff;
+            border-radius: 50%;
+            animation: spin 1s linear infinite;
+            margin-right: 10px;
+        }
+        @keyframes spin {
+            0% { transform: rotate(0deg); }
+            100% { transform: rotate(360deg); }
+        }
+        ${testModeIndicators.showTestBadges !== false ? `
+        .test-badge {
+            display: inline-block;
+            background: #6c757d;
+            color: white;
+            padding: 4px 8px;
+            border-radius: 4px;
+            font-size: 12px;
+            font-weight: 600;
+            text-transform: uppercase;
+            margin-left: 8px;
+        }
+        ` : ''}
+    </style>
+</head>
+<body>
+    <div class="container">
+        ${testModeIndicators.showWarningBanners !== false ? `
+        <div class="test-banner">
+            🧪 TEST MODE - This is a simulated payment for development purposes
+        </div>
+        ` : ''}
+
+        <div class="header">
+            <div class="title">
+                Test Payment Checkout
+                ${testModeIndicators.showTestBadges !== false ? '<span class="test-badge">Test</span>' : ''}
+            </div>
+            <div class="amount">${payment.currency?.toUpperCase()} ${(payment.amount / 100).toFixed(2)}</div>
+            ${payment.description ? `<div class="description">${payment.description}</div>` : ''}
+        </div>
+
+        <div class="content">
+            <div class="section">
+                <div class="section-title">
+                    💳 Select Payment Method
+                </div>
+                <div class="payment-methods">
+                    ${Object.entries(PAYMENT_METHODS).map(([key, method]) => `
+                        <div class="method" data-method="${key}">
+                            <div class="method-icon">${method.icon}</div>
+                            <div class="method-name">${method.name}</div>
+                        </div>
+                    `).join('')}
+                </div>
+            </div>
+
+            <div class="section">
+                <div class="section-title">
+                    🎭 Select Test Scenario
+                </div>
+                <div class="scenarios">
+                    ${scenarios.map(scenario => `
+                        <div class="scenario" data-scenario="${scenario.id}">
+                            <div class="scenario-name">${scenario.name}</div>
+                            <div class="scenario-desc">${scenario.description}</div>
+                        </div>
+                    `).join('')}
+                </div>
+            </div>
+
+            <button class="process-btn" id="processBtn" disabled>
+                Process Test Payment
+            </button>
+
+            <div id="status" class="status" style="display: none;"></div>
+        </div>
+    </div>
+
+    <script>
+        let selectedMethod = null;
+        let selectedScenario = null;
+
+        // Payment method selection
+        document.querySelectorAll('.method').forEach(method => {
+            method.addEventListener('click', () => {
+                document.querySelectorAll('.method').forEach(m => m.classList.remove('selected'));
+                method.classList.add('selected');
+                selectedMethod = method.dataset.method;
+                updateProcessButton();
+            });
+        });
+
+        // Scenario selection
+        document.querySelectorAll('.scenario').forEach(scenario => {
+            scenario.addEventListener('click', () => {
+                document.querySelectorAll('.scenario').forEach(s => s.classList.remove('selected'));
+                scenario.classList.add('selected');
+                selectedScenario = scenario.dataset.scenario;
+                updateProcessButton();
+            });
+        });
+
+        function updateProcessButton() {
+            const btn = document.getElementById('processBtn');
+            btn.disabled = !selectedMethod || !selectedScenario;
+        }
+
+        // Process payment
+        document.getElementById('processBtn').addEventListener('click', async () => {
+            const btn = document.getElementById('processBtn');
+            const status = document.getElementById('status');
+
+            btn.disabled = true;
+            btn.innerHTML = '<span class="loading"></span>Processing...';
+
+            try {
+                const response = await fetch('/api/payload-billing/test/process', {
+                    method: 'POST',
+                    headers: { 'Content-Type': 'application/json' },
+                    body: JSON.stringify({
+                        paymentId: '${session.id}',
+                        scenarioId: selectedScenario,
+                        method: selectedMethod
+                    })
+                });
+
+                const result = await response.json();
+
+                if (result.success) {
+                    status.className = 'status processing';
+                    status.style.display = 'block';
+                    status.innerHTML = \`<span class="loading"></span>Processing payment with \${result.scenario}...\`;
+
+                    // Poll for status updates
+                    setTimeout(() => pollStatus(), result.delay || 1000);
+                } else {
+                    throw new Error(result.error || 'Failed to process payment');
+                }
+            } catch (error) {
+                status.className = 'status error';
+                status.style.display = 'block';
+                status.textContent = 'Error: ' + error.message;
+                btn.disabled = false;
+                btn.textContent = 'Process Test Payment';
+            }
+        });
+
+        async function pollStatus() {
+            try {
+                const response = await fetch('/api/payload-billing/test/status/${session.id}');
+                const result = await response.json();
+
+                const status = document.getElementById('status');
+                const btn = document.getElementById('processBtn');
+
+                if (result.status === 'paid') {
+                    status.className = 'status success';
+                    status.textContent = '✅ Payment successful!';
+                    setTimeout(() => {
+                        window.location.href = '${baseUrl}/success';
+                    }, 2000);
+                } else if (result.status === 'failed' || result.status === 'cancelled' || result.status === 'expired') {
+                    status.className = 'status error';
+                    status.textContent = \`❌ Payment \${result.status}\`;
+                    btn.disabled = false;
+                    btn.textContent = 'Try Again';
+                } else if (result.status === 'pending') {
+                    status.className = 'status processing';
+                    status.innerHTML = '<span class="loading"></span>Payment is still pending...';
+                    setTimeout(() => pollStatus(), 2000);
+                }
+            } catch (error) {
+                console.error('Failed to poll status:', error);
+            }
+        }
+
+        ${testModeIndicators.consoleWarnings !== false ? `
+        console.warn('🧪 TEST MODE: This is a simulated payment interface for development purposes');
+        ` : ''}
+    </script>
+</body>
+</html>`
+}