# Tests Audit Report

**Branch**: fix/issue-28-graph-corruption-shallow-copy
**Base**: main
**Date**: 2025-11-28 11:04:00

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## Executive Summary

This PR introduces 8 new tests covering two critical fixes:
1. **Graph Corruption Fix (Issue #28)**: 3 regression tests for `DependencyGraph.wouldCreateCycle()` immutability
2. **Settling Workers Tracking**: 5 tests for `SystemResourceMonitor.recordSpawn()` functionality

**Tests Score**: 8/10

**Merge Recommendation**: APPROVED

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## New Tests Analysis

### 1. DependencyGraph Immutability Tests (Issue #28)

**File**: `/workspace/delegate/tests/unit/core/dependency-graph.test.ts`
**Lines Added**: 248-338 (describe block "Cycle Detection - Immutability (Issue #28)")

#### Test 1: `should not mutate graph when checking for cycles with existing task`
- **Purpose**: Regression test for shallow copy bug
- **Quality**: EXCELLENT
- **Coverage**: Tests exact bug scenario - A->B edge exists, check B->A would create cycle
- **Assertions**: Verifies graph size, dependencies before/after cycle check
- **Critical assertion**: `expect(depsBAfter.value).not.toContain(TaskId('task-A'))` - catches the exact bug

#### Test 2: `should not mutate graph when checking non-cycle with existing task`
- **Purpose**: Verifies immutability even when no cycle detected
- **Quality**: GOOD
- **Coverage**: Edge case - cycle check that returns false
- **Assertions**: Size unchanged, no phantom edges added

#### Test 3: `should not mutate graph with multiple cycle checks`
- **Purpose**: Tests accumulated corruption from multiple checks
- **Quality**: GOOD
- **Coverage**: Multiple cycle checks on same graph
- **Assertions**: Verifies C has no dependencies after 4 cycle checks

### 2. Settling Workers Tests

**File**: `/workspace/delegate/tests/unit/implementations/system-resource-monitor.test.ts`
**Lines Added**: 205-292 (describe block "Settling workers tracking")

#### Test 1: `should record spawn events`
- **Purpose**: Basic recordSpawn() functionality
- **Quality**: MINIMAL but appropriate
- **Coverage**: Smoke test only
- **Assertions**: Just `expect(() => monitor.recordSpawn()).not.toThrow()`

#### Test 2: `should include settling workers in effective worker count`
- **Purpose**: Verifies settling workers affect canSpawnWorker()
- **Quality**: GOOD
- **Coverage**: Multiple spawns recorded
- **Note**: Could use more specific assertion on behavior

#### Test 3: `should expire settling workers after 15 second window`
- **Purpose**: Verifies timestamp cleanup
- **Quality**: GOOD
- **Coverage**: Uses fake timers to advance 16 seconds
- **Assertions**: Verifies canSpawnWorker() returns ok after expiry

#### Test 4: `should not expire settling workers within the window`
- **Purpose**: Boundary condition - workers still tracked before expiry
- **Quality**: GOOD
- **Coverage**: Advances 10 seconds (within 15s window)

#### Test 5: `should correctly project resource usage for settling workers`
- **Purpose**: Integration test with MAX_WORKERS limit
- **Quality**: EXCELLENT
- **Coverage**: Tests settling workers count toward max limit
- **Assertions**: `expect(result.value).toBe(false)` when at limit

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## Category Analysis

### Category 1: Issues in Your Changes (BLOCKING)

None found. All new tests are well-structured and pass.

### Category 2: Issues in Code You Touched (Should Fix)

**1. [MEDIUM] Settling Workers Test Missing Negative Scenario**
- **File**: `/workspace/delegate/tests/unit/implementations/system-resource-monitor.test.ts`
- **Line**: 218-221
- **Issue**: Test `should record spawn events` only verifies no throw, doesn't verify internal state
- **Impact**: Could miss bugs where recordSpawn() silently fails
- **Suggestion**: Add assertion that verifies settling worker count increased

**2. [MEDIUM] No Test for recordSpawn() Optional Chaining in WorkerHandler**
- **File**: `/workspace/delegate/src/services/handlers/worker-handler.ts:296`
- **Issue**: `this.resourceMonitor.recordSpawn?.()` uses optional chaining but no test verifies behavior when method doesn't exist
- **Impact**: Interface compatibility not fully tested
- **Suggestion**: Add test with mock ResourceMonitor that lacks recordSpawn()

**3. [LOW] Settling Workers Test Could Verify Projected Resource Calculation**
- **File**: `/workspace/delegate/tests/unit/implementations/system-resource-monitor.test.ts`
- **Line**: 260-291
- **Issue**: Tests verify behavior but don't verify the actual projected memory/CPU calculations
- **Suggestion**: Add test that verifies projectedCoresUsed = settlingWorkers * CORES_PER_WORKER

### Category 3: Pre-existing Issues (Not Blocking)

**1. [INFO] TestResourceMonitor.recordSpawn() is a no-op**
- **File**: `/workspace/delegate/src/implementations/resource-monitor.ts:413-415`
- **Issue**: `recordSpawn(): void { /* No-op */ }` means tests using TestResourceMonitor don't actually test settling behavior
- **Impact**: Integration tests may not catch settling worker issues
- **Note**: This is appropriate for unit tests but limits integration testing

**2. [INFO] Skipped Tests in SystemResourceMonitor**
- **File**: `/workspace/delegate/tests/unit/implementations/system-resource-monitor.test.ts`
- **Lines**: 305-376
- **Issue**: 3 tests marked with `it.skip` for threshold crossing events
- **Note**: TODOs indicate features not yet implemented - not a test quality issue

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## Test Coverage Assessment

### New Code Coverage

| File | New Code | Tested |
|------|----------|--------|
| `src/core/dependency-graph.ts:249-255` | Deep copy fix | YES - 3 regression tests |
| `src/implementations/resource-monitor.ts:27-31` | SETTLING_WINDOW_MS constant | YES |
| `src/implementations/resource-monitor.ts:79-97` | Settling workers in canSpawnWorker | YES - boundary tests |
| `src/implementations/resource-monitor.ts:108-111` | Projected resource calculations | PARTIAL - behavior tested, not calculations |
| `src/implementations/resource-monitor.ts:171-181` | recordSpawn() method | YES |
| `src/core/interfaces.ts:50-55` | recordSpawn interface | YES - via implementation |
| `src/services/handlers/worker-handler.ts:296` | recordSpawn call | NO - missing unit test |

### Missing Edge Cases

1. **Graph Corruption with Concurrent Operations**: No test for thread safety (likely not an issue in Node.js single-threaded model)
2. **Settling Workers Cleanup Race**: No test for cleanup during active spawn decision
3. **recordSpawn() Called After Monitor Stopped**: No test for lifecycle edge case

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## Test Quality Metrics

| Metric | Score | Notes |
|--------|-------|-------|
| Arrange-Act-Assert Pattern | 9/10 | All tests follow AAA pattern clearly |
| Test Isolation | 9/10 | Each test uses fresh monitor/graph instance |
| Assertion Quality | 8/10 | Good assertions, could verify more internals |
| Edge Case Coverage | 7/10 | Time boundaries tested, some gaps |
| Documentation | 9/10 | Excellent comments explaining bug scenarios |
| Maintainability | 9/10 | Clean structure, data-driven where appropriate |

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## Summary

**Your Changes:**
- 0 CRITICAL
- 0 HIGH
- 2 MEDIUM (missing test for optional chaining, missing state verification)
- 1 LOW (calculation verification)

**Code You Touched:**
- No additional issues beyond your changes

**Pre-existing:**
- 2 INFO (no-op in TestResourceMonitor, skipped tests)

**Tests Score**: 8/10

**Verdict**: The new tests adequately cover the critical bug fix (Issue #28) with excellent regression tests. The settling workers feature has good coverage but could benefit from one or two additional edge case tests. The tests follow best practices and are well-documented.

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## Recommendations

### Before Merge (Optional Improvements)
1. Consider adding test verifying `recordSpawn()` actually increases internal counter
2. Consider adding test for WorkerHandler with ResourceMonitor lacking `recordSpawn()`

### After Merge (Technical Debt)
1. Implement the skipped threshold event tests when feature is built
2. Consider adding integration test that uses SystemResourceMonitor (not TestResourceMonitor) for settling behavior

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*Generated by Claude Code Tests Audit*
