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🧪 Mock Services

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How it Works

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Automatic Detection Example

// apps/app/app/services/mocks/index.ts (simplified)
export const USE_MOCK_SUPABASE = __DEV__ && !process.env.EXPO_PUBLIC_SUPABASE_URL
export const USE_MOCK_POSTHOG = __DEV__ && !process.env.EXPO_PUBLIC_POSTHOG_API_KEY
// ... and so on for other services

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Benefits of Mock Mode

• Frontend-First Development: Start building your UI and user experience immediately, without waiting for backend setup or API key configuration.
• Rapid Prototyping: Quickly iterate on features and designs without external dependencies.
• Offline Development: Work on your app even without an internet connection.
• Simplified Testing: Easily test various scenarios (e.g., different subscription states, empty data sets) by manipulating mock data.
• Reduced Costs: Avoid incurring costs from third-party services during early development.

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Available Mock Services

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Mock Service Capabilities

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1. Supabase Mock

• Authentication:
  • ✅ Sign up, sign in, sign out with email/password.
  • ✅ Session management (persists in SecureStore).
  • ✅ Password reset (simulated).
  • ✅ User updates and auth state listeners.
  • ✅ OAuth (Google, Apple, GitHub, Twitter) flow simulation.
• Database:
  • ✅ Full CRUD operations (Create, Read, Update, Delete).
  • ✅ All standard query filters (eq, neq, gt, gte, lt, lte, like, ilike, in).
  • ✅ Ordering, limiting, and pagination (order, limit, range).
  • ✅ Single row queries (single(), maybeSingle()).
  • ✅ Upsert operations.
  • ✅ In-memory storage with optional SecureStore persistence.
• Storage:
  • ✅ File upload (upload()), download (download()), and removal (remove()).
  • ✅ List files (list()).
  • ✅ Public URLs (getPublicUrl()) and signed URLs (createSignedUrl()).
  • ✅ Bucket management.
• Realtime:
  • ✅ Channel subscriptions.
  • ✅ Postgres changes (INSERT, UPDATE, DELETE) simulation.
  • ✅ Programmatic event triggering for testing.
• RPC (Remote Procedure Call):
  • ✅ Register custom RPC handlers to simulate stored procedures.

import { supabase } from '@/services/supabase'
// Authentication
const { error: signInError } = await supabase.auth.signInWithPassword({ email: 'test@example.com', password: 'password' })

// Database Query
const { data: posts, error: postsError } = await supabase
  .from('posts')
  .select('*')
  .eq('author_id', 'some-user-id')
  .order('created_at', { ascending: false })
  .limit(10)

// Storage Upload
const fileBlob = new Blob(['hello world'], { type: 'text/plain' });
const { data: uploadData, error: uploadError } = await supabase.storage
  .from('avatars')
  .upload('my-file.txt', fileBlob, { contentType: 'text/plain' })

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2. PostHog Mock

• Analytics: Event tracking, screen tracking, user identification, user properties, groups.
• Feature Flags: Simulated feature flag checks (isFeatureEnabled, getFeatureFlag).
• Opt-in/Opt-out: Simulated behavior.

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3. Sentry Mock

• Error Tracking: Exception capturing, message logging, breadcrumbs, user context, tags, and extra data.
• Performance Monitoring: Simulated performance transaction logging.

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4. RevenueCat Mock

• Subscriptions: Purchase flow (always succeeds), restore purchases, get offerings/packages, customer info, entitlements, subscription states.

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Testing Utilities

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Supabase Mock Testing Utilities

import { mockSupabaseHelpers } from '@/services/mocks/supabase'
// Seed database tables with test data
mockSupabaseHelpers.seedTable('posts', [
  { id: 1, title: 'Welcome Post', content: 'This is a test post', author_id: 'mock-user-123' },
])
mockSupabaseHelpers.seedTable('profiles', [
  { id: 'mock-user-123', email: 'test@example.com', first_name: 'Test', last_name: 'User' },
])

// Get current data from a mock table
const posts = mockSupabaseHelpers.getTableData('posts')

// Clear all mock data
mockSupabaseHelpers.clearAll()

// Simulate an error for a specific Supabase method
mockSupabaseHelpers.simulateError('database', 'posts.select', new Error('Network unavailable'))

// Trigger a realtime event for testing subscriptions
mockSupabaseHelpers.triggerRealtimeEvent('posts', 'INSERT', { id: 3, title: 'New Realtime Post' })

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RevenueCat Mock Testing Utilities

import { mockRevenueCat } from '@/services/mocks/revenueCat'
// Simulate a user having 'pro' status
mockRevenueCat.setProStatus(true)

// Check current 'pro' status
const isPro = mockRevenueCat.getIsPro()

// Reset mock RevenueCat state
mockRevenueCat.reset()

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Mock Service Behavior Details

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Data Persistence

• During App Session: Mock data persists in memory throughout the app’s current session. Authentication sessions are maintained, and database queries work across components.
• On App Restart: All mock data is cleared, and the user is logged out. Database tables will be empty.
  • Solution for Testing: Use mockSupabaseHelpers.seedTable() in your app’s initialization logic or test setup to re-populate data.

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Network Delays

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Console Logging

🔐 [MockSupabase] Sign in: user@example.com
💾 [MockSupabase] SELECT * FROM posts
📊 [MockPostHog] Event: button_clicked
🐛 [MockSentry] Exception: Error message
💰 [MockRevenueCat] Purchase: pro_monthly

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Transitioning to Production

# Example .env with real API keys
EXPO_PUBLIC_SUPABASE_URL=https://your-project.supabase.co
EXPO_PUBLIC_SUPABASE_ANON_KEY=your-anon-key
EXPO_PUBLIC_POSTHOG_API_KEY=your-posthog-key
EXPO_PUBLIC_SENTRY_DSN=your-sentry-dsn
EXPO_PUBLIC_REVENUECAT_IOS_KEY=your-rc-ios-key
# ... etc.

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Limitations

• Row Level Security (RLS): Mock Supabase does not enforce RLS policies.
• Advanced Database Features: Complex database functions, triggers, or highly specific filters might not be fully supported.
• Performance Testing: Mocks do not accurately reflect the performance characteristics of real backend services.