What is mock-data-finder?

The Mock Data Finder is a specialized Claude skill designed to detect and eliminate silent mock data fallbacks within Android and iOS applications. It helps developers identify code patterns where API failures are masked by hardcoded data, ensuring that real errors are surfaced and handled correctly. By scanning for specific Kotlin and Swift patterns, it improves app reliability, simplifies troubleshooting, and prevents misleading UI states in production environments.

When should I use mock-data-finder?

mock-data-finder is useful in the following scenarios: • Debugging mobile screens that display 'fake' data to determine why real API responses are not loading or being ignored. • Performing code audits in Android (Kotlin) and iOS (Swift) projects to replace silent catch-block fallbacks with proper error logging and retry UI. • Identifying and removing hardcoded test IDs, 'getMock' functions, and preview data before a production release to ensure data integrity. • Improving application observability by ensuring that network failures trigger legitimate error states rather than returning static mock objects.

name	mock-data-finder
description	Find and remove silent mock data fallbacks in Android/iOS screens. Use when screens show fake data, when debugging why real API data isn't loading, or to ensure proper error handling instead of mock fallbacks.
allowed-tools	Read, Grep, Glob, Edit

Mock Data Finder

Purpose

Find Android and iOS screens that silently fall back to mock data when API calls fail, hiding real errors from users and developers.

Why This Matters

Silent mock data fallbacks:

Hide API errors making debugging difficult
Show fake data to users (misleading)
Prevent proper error handling/retry UI
Make it impossible to know if API is working

Detection Patterns

Android (Kotlin)

Look for catch blocks that load mock data:

// BAD: Silent fallback to mock
} catch (e: Exception) {
    state = state.copy(
        loading = false,
        data = getMockData()  // User sees fake data!
    )
}

// GOOD: Show error, let user retry
} catch (e: Exception) {
    Log.e("Screen", "API failed", e)
    state = state.copy(
        loading = false,
        error = "Failed to load: ${e.message}"
    )
}

Search Commands

Find mock data in Android:

# Find getMock functions
grep -r "getMock" apps/android/ --include="*.kt"

# Find mock fallbacks in catch blocks
grep -rn "catch.*Exception" apps/android/ --include="*.kt" -A 5 | grep -i mock

# Find hardcoded test data
grep -rn "listOf\|arrayOf" apps/android/*/ui/screens/ --include="*.kt" | grep -E "(id.*=.*\".*-\"|test|mock|fake)"

Find mock data in iOS:

# Find mock/preview data
grep -r "mock\|Mock\|preview\|Preview" apps/ios/ --include="*.swift"

# Find catch blocks with fallbacks
grep -rn "catch" apps/ios/ --include="*.swift" -A 3

Common Mock Data Patterns

Pattern 1: getMockXxx() Function

fun getMockDashboard(): Dashboard {
    return Dashboard(
        items = listOf(
            Item(id = "mock-1", name = "Test Item")
        )
    )
}

Pattern 2: Inline Mock in Catch

catch (e: Exception) {
    val mockData = listOf(
        User(id = "u1", name = "John Doe"),
        User(id = "u2", name = "Jane Doe")
    )
    state = state.copy(users = mockData)
}

Pattern 3: Conditional Mock Fallback

val data = apiResponse ?: getMockData()
// or
val data = if (apiResponse.isEmpty()) getMockData() else apiResponse

Fix Pattern

Replace mock fallbacks with proper error handling:

// BEFORE
fun loadData() {
    scope.launch {
        state = state.copy(loading = true)
        try {
            val data = apiService.getData()
            state = state.copy(loading = false, data = data)
        } catch (e: Exception) {
            // Silent mock fallback - BAD!
            state = state.copy(loading = false, data = getMockData())
        }
    }
}

// AFTER
fun loadData() {
    scope.launch {
        state = state.copy(loading = true, error = null)
        try {
            val data = apiService.getData()
            state = state.copy(loading = false, data = data)
        } catch (e: Exception) {
            // Log error and show to user - GOOD!
            Log.e("ScreenName", "Failed to load data", e)
            state = state.copy(
                loading = false,
                error = "Failed to load data: ${e.message}"
            )
        }
    }
}

Checklist

When reviewing a screen:

No getMock*() functions called in production code
Catch blocks log errors with Log.e()
Catch blocks set error state, not mock data
UI has error state display (error banner, retry button)
No hardcoded test IDs ("test-1", "mock-id", etc.)

Files to Check

Common locations for mock data:

Android:

apps/android/**/ui/screens/*.kt - Screen composables
apps/android/**/ui/viewmodels/*.kt - ViewModels
apps/android/**/data/repository/*.kt - Repositories

iOS:

apps/ios/**/Views/*.swift - SwiftUI views
apps/ios/**/ViewModels/*.swift - ViewModels
apps/ios/**/Services/*.swift - API services

mock-data-finder

When & Why to Use This Skill

Use Cases