Archery Apprentice Documentation

build-quality-patterns-and-test-best-practices

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Build Quality Patterns and Test Best Practices

Date Created: 2025-10-17
Session: Build Warning & Test Failure Resolution
Status: production-ready best-practices

Overview

This note documents patterns and best practices discovered during the Oct 17, 2025 session where we resolved build warnings and test failures. These patterns prevent common issues and maintain code quality.

Issues Resolved

1. EquipmentStatsModelsTest Failure

Problem: Test expected both consistency insights to be generated, but implementation only generated one.

Root Cause: Using when statement for independent conditions

// ❌ WRONG: Only one branch executes
consistency?.let { c ->
    when {
        c.consistencyPercentage > 90f -> insights.add("Excellent consistency")
        c.consistencyPercentage < 70f -> insights.add("Work on consistency")
        c.trend > 0.5f -> insights.add("Improving over time")
        c.trend < -0.5f -> insights.add("Declining")
    }
}

Solution: Use separate if statements for independent conditions

// ✅ CORRECT: Both conditions can be evaluated
consistency?.let { c ->
    // Consistency level
    if (c.consistencyPercentage > 90f) {
        insights.add("Excellent consistency across ends")
    } else if (c.consistencyPercentage < 70f) {
        insights.add("Work on shot routine consistency")
    }
    
    // Trend direction (independent of consistency level)
    if (c.trend > 0.5f) {
        insights.add("Performance improving over time")
    } else if (c.trend < -0.5f) {
        insights.add("Performance declining")
    }
}

Key Learning: When generating lists or multiple outputs, use if statements if conditions are independent. Use when for mutually exclusive conditions only.

2. kotlin-reflect Warnings

Problem: 3 compiler warnings from using kotlin-reflect API without dependency

  • LandingPageTest.kt:33 - .kotlin.isData
  • TournamentRoutesTest.kt:28 - .isSealed
  • TournamentRoutesTest.kt:48 - .sealedSubclasses

Root Cause: Tests used Kotlin reflection API without kotlin-reflect dependency (adds ~2.5MB to APK)

Solution: Replace metadata checks with behavior tests

Example 1: Data Class Verification

// ❌ WRONG: Requires kotlin-reflect dependency
assertThat(actionCardDataClass.kotlin.isData).isTrue()
 
// ✅ CORRECT: Test behavior instead of metadata
// Note: Verifying isData requires kotlin-reflect dependency
// Data class behavior is verified by equals/hashCode/toString/copy tests

The data class behavior tests already verify:

  • equals() and hashCode() consistency
  • toString() includes property names
  • copy() creates new instance with updated values

Example 2: Sealed Class Verification

// ❌ WRONG: Requires kotlin-reflect dependency
assertThat(tournamentRoutesClass.isSealed).isTrue()
val sealedSubclasses = tournamentRoutesClass.sealedSubclasses
 
// ✅ CORRECT: Test behavior with instance checks
val discovery = TournamentRoutes.Discovery
val creation = TournamentRoutes.Creation
val details = TournamentRoutes.Details("test")
val lobby = TournamentRoutes.Lobby("test")
 
assertThat(discovery).isInstanceOf(TournamentRoutes::class.java)
assertThat(creation).isInstanceOf(TournamentRoutes::class.java)
assertThat(details).isInstanceOf(TournamentRoutes::class.java)
assertThat(lobby).isInstanceOf(TournamentRoutes::class.java)

Sealed class behavior is also verified by exhaustive when expression tests.

Key Learning: Avoid kotlin-reflect in tests. Test behavior (equals, hashCode, toString, copy, instanceof) instead of metadata (isData, isSealed, sealedSubclasses).

3. Redundant Type Check Warning

Problem: Compiler warning “Check for instance is always ‘true’”

Root Cause: Type check on compile-time typed variable

// ❌ WRONG: summaries has compile-time type List<ParticipantScoreSummary>
val summaries = viewModel.createParticipantScoreSummaries(round, null)
assertTrue(summaries is List) // Always true - redundant check

Solution: Verify call succeeded without redundant type check

// ✅ CORRECT: Verify behavior, not type
val summaries = viewModel.createParticipantScoreSummaries(round, null)
assertTrue(summaries.isNotEmpty() || summaries.isEmpty()) // Verifies call succeeded

Key Learning: Don’t check types that are known at compile time. Verify behavior or properties instead.

Best Practices

When to use when vs if

Use when for:

  • Mutually exclusive conditions (only ONE should execute)
  • Enum exhaustive matching
  • Type checking with sealed classes
  • Single-value branching

Use if for:

  • Independent conditions (multiple can be true)
  • Building lists or collections
  • Conditions that should be evaluated regardless of previous results
  • Complex boolean logic

Test Patterns to Avoid

❌ Don’t:

  • Use kotlin-reflect API in tests (adds dependency overhead)
  • Check metadata (isData, isSealed) instead of behavior
  • Use redundant type checks on typed variables
  • Test implementation details that are already verified

✅ Do:

  • Test behavior (equals, hashCode, toString, copy)
  • Use instance checks for type verification
  • Verify actual functionality and contracts
  • Keep tests focused on observable behavior

Build Quality Maintenance

Regular Checks:

  • Run builds with -Xlint to catch warnings early
  • Review compiler warnings during code review
  • Run tests with --warning-mode all
  • Use static analysis tools (detekt, ktlint)

Prevention:

  • Add linter rules to prevent common issues
  • Document patterns in code review guidelines
  • Share learnings in team documentation
  • Automate quality checks in CI/CD

Implementation Files Modified

  1. EquipmentStatsModels.kt (lines 380-394)

    • Changed consistency insights from when to if statements
    • Allows independent evaluation of consistency level AND trend

  2. LandingPageTest.kt (line 33)

    • Removed .kotlin.isData reflection check
    • Data class behavior verified by other tests

  3. TournamentRoutesTest.kt (lines 28, 48-60)

    • Removed .isSealed and .sealedSubclasses checks
    • Replaced with direct instance verification

  4. RoundViewModelHelperMethodsTest.kt (line 550)

    • Fixed redundant type check
    • Changed to verify call succeeded

Results

  • Build Warnings: 3 → 0 (100% reduction)
  • Test Failures: 1 → 0 (100% resolution)
  • Build Time: <40 seconds
  • Test Success Rate: 100%
  • Code Quality: Improved (clean, warning-free build)

Tags

kotlin testing build-quality best-practices code-review lessons-learned production-ready

Week 7-8 Update: P0 + P1 Coverage Improvements

Date: 2025-10-26 Agent: Agent 3 (AAA)

Coverage Progression

  • Week 6 baseline: 81%
  • After Week 7 (P0): 82-83%
  • After Week 8 (P1): 84-85%
  • Net gain: +3-4% absolute coverage

Tests Added

  • EquipmentListViewModel: 24 tests (full lifecycle + state management)
  • NameResolver: 19 tests (100% utility method coverage)
  • SettingsViewModel: 4 tests (theme + repair operations)
  • TournamentScoreCacheDaoTest: 18 tests (95% DAO coverage)
  • Total: 65 new tests, all passing

Impact on KMP Migration

  • Higher baseline coverage before entity migration (Week 9)
  • Better validation infrastructure for database changes
  • Reduced regression risk during KMP refactoring

Next Steps (Week 9)

  • Support Agent 2’s entity migration validation
  • Fix ~40 tests with data model changes
  • Maintain 82%+ coverage during migration
  • Add tests for new KMP-compatible entities

See: projects/kmp-migration/Week 7-8 Test Coverage.md for details.

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