Mobile Verification Skill

Comprehensive testing workflow with pass@k metrics for Android development reliability.

Philosophy

Single test runs lie.

A test that passes once might fail tomorrow. Verification loops run tests multiple times to reveal:

• Flaky tests (timing issues, async problems)
• Intermittent failures (resource contention)
• Reliability trends (improving vs degrading)

Pass@k Explained

Pass@k = proportion of test iterations that passed

Pass@3(test) = tests_passed / 3

testLogin(): ✓✓✓ → Pass@3 = 3/3 = 1.0 (100%)
testLogout(): ✓✓✗ → Pass@3 = 2/3 = 0.67 (67%)
testRefresh(): ✗✗✗ → Pass@3 = 0/3 = 0.0 (0%)

Verification Levels

Quick Verification (k=2)

Purpose: Fast feedback during development
Usage: /mobile-verify --k=2
Time: ~2 minutes
When: After small changes, before commit

Standard Verification (k=3)

Purpose: Standard confidence level
Usage: /mobile-verify --k=3
Time: ~5 minutes
When: Before push, after feature complete

Thorough Verification (k=5)

Purpose: High confidence, flaky detection
Usage: /mobile-verify --k=5
Time: ~10 minutes
When: Before release, after refactor

Release Verification (k=10)

Purpose: Maximum confidence
Usage: /mobile-verify --k=10
Time: ~20 minutes
When: Production release, critical bugs

Test Type Strategies

Unit Tests (JUnit)

Characteristics:

• Fast: ~1-2 seconds per test
• Isolated: No Android dependencies
• Reliable: Should be Pass@k = 1.0

Target Pass@k: ≥ 0.95 (95%)

Common Flaky Causes:

• Async operations without proper waiting
• Date/time dependencies
• Random data generation
• Static state leakage

Fix Strategies:

// Bad: Flaky
@Test
fun testLoadData() {
    viewModel.loadData()
    assert(viewModel.state.value is Loaded)
}

// Good: Stable
@Test
fun testLoadData() = runTest {
    viewModel.loadData()
    advanceUntilIdle()
    assert(viewModel.state.value is Loaded)
}

UI Tests (Espresso)

Characteristics:

• Slow: ~5-10 seconds per test
• Device-dependent: Need emulator/device
• Fragile: UI changes break tests

Target Pass@k: ≥ 0.80 (80%)

Common Flaky Causes:

• Idling resource not registered
• Animation interference
• Screen rotation
• Network timeouts

Fix Strategies:

// Register idling resources
@IdlingResource
val countingIdlingResource = CountingIdlingResource("api")

// Disable animations
@get:Rule
val disableAnimationsRule = DisableAnimationsRule()

Compose Tests

Characteristics:

• Fast: ~1-3 seconds per test
• UI-level: Tests Composable behavior
• Modern: Uses Compose Testing framework

Target Pass@k: ≥ 0.90 (90%)

Common Flaky Causes:

• Recomposition timing
• State hoisting issues
• Animation interference

Fix Strategies:

@Composable
fun TestComposable(content: @Composable () -> Unit) {
    CompositionLocalProvider(
        LocalInspectionMode provides true
    ) {
        content()
    }
}

Verification Workflow

During Development

# 1. Write test
# 2. Quick verify
/mobile-verify --class=NewTest --k=2

# 3. Fix if fails
# 4. Standard verify
/mobile-verify --class=NewTest --k=3

Before Commit

# Verify changed modules only
/mobile-verify --module=$(git diff --name-only | head -1) --k=2

Before Push

# Full verification
/mobile-verify --k=3

Before Release

# Thorough verification with flaky detection
/mobile-verify --k=5 --flaky

Interpreting Results

Pass@k Scores

Trends

Track pass@k over time:

Week 1: Pass@3 = 0.85
Week 2: Pass@3 = 0.87  ↗ Improving
Week 3: Pass@3 = 0.82  ↘ Degraded - investigate!
Week 4: Pass@3 = 0.88  ↗ Recovered

Flaky Test Patterns

Fixing Flaky Tests

Step 1: Identify Pattern

/mobile-verify --flaky --k=10

Look for patterns in failures.

Step 2: Add Diagnostics

@Test
fun flakyTest() = runTest {
    val startTime = System.currentTimeMillis()
    // ... test code ...
    val duration = System.currentTimeMillis() - startTime
    Log.d("Test", "Duration: $duration ms")  // Check for timing issues
}

Step 3: Apply Fix

Common fixes:

• Add advanceUntilIdle() for coroutines
• Add IdlingResource for network
• Disable animations for UI tests
• Use @UiThreadTest for main thread work
• Add explicit waits for async operations

Step 4: Verify Fix

/mobile-verify --class=FixedTest --k=5

Target: Pass@5 = 1.0

Integration

With Checkpoints

Create checkpoint before verification:

/mobile-checkpoint save pre-verify
/mobile-verify --k=3

With Memory

Track pass@k in memory:

{
    "test-coverage": {
        "passAt3": 0.87,
        "trend": "improving",
        "flakyTests": []
    }
}

With Instincts

Learn testing patterns:

{
    "id": "test-coroutine-async",
    "description": "Always use runTest + advanceUntilIdle for ViewModel tests",
    "confidence": 0.95
}

Thresholds by Context

Best Practices

1. Start High, Go Low: Use k=5 for investigation, k=3 for routine
2. Fix Flaky Fast: Don't tolerate flaky tests
3. Track Trends: Monitor pass@k over time
4. Context Matters: UI tests can have lower thresholds than unit
5. Block Release: Failed verification should block releases

Remember: A test that sometimes passes is worse than no test at all. It gives false confidence.