Tdd Refactor Guard Skill for Claude

Without guard:               With guard:
"Claude, refactor this"      "Claude, refactor this"
  → AI rewrites code           → Guard checks for tests
  → Something breaks           → Tests missing → generate them
  → You don't know what        → Tests pass → proceed with refactor
  → Debugging nightmare         → Tests fail → exact regression found

Ask user: "Which files/classes are you planning to refactor?"

Glob: [files mentioned in conversation]
Read: each file to understand scope

Grep: "class.*Tests.*XCTestCase|@Suite.*Tests|struct.*Tests" in test targets
Grep: "@Test|func test" that reference the classes being refactored

// ❌ Low-quality test — doesn't actually verify behavior
@Test("test items")
func testItems() {
    let vm = ViewModel()
    vm.loadItems()
    #expect(true)  // Always passes, tests nothing
}

// ❌ Tests implementation, not behavior
@Test("calls repository")
func testCallsRepo() {
    let vm = ViewModel()
    vm.loadItems()
    #expect(mockRepo.fetchCallCount == 1)  // Brittle
}

// ✅ Tests observable behavior
@Test("loads items into published array")
func testLoadsItems() async {
    let vm = ViewModel(repo: MockRepo(items: [.sample]))
    await vm.loadItems()
    #expect(vm.items.count == 1)
    #expect(vm.items.first?.title == "Sample")
}

Before refactoring [ClassName], generate characterization tests:
1. Read the source file
2. Identify all public methods
3. Generate tests that capture CURRENT behavior
4. Run and verify all pass

## Refactor Guard: ✅ PROCEED

**Files**: ItemManager.swift, ItemRepository.swift
**Test coverage**: Good (12 tests covering 8/9 public methods)
**Test quality**: Adequate — tests verify behavior, not implementation

Safe to refactor. Run tests after each change:
`xcodebuild test -scheme YourApp`

## Refactor Guard: ⚠️ NEEDS TESTS

**Files**: ItemManager.swift, ItemRepository.swift
**Test coverage**: Partial (5 tests covering 4/9 public methods)
**Missing coverage**:
- `ItemManager.sort()` — no test
- `ItemManager.filter(by:)` — no test
- `ItemRepository.sync()` — no test
- Error paths for `save()` and `delete()` — not tested

**Action**: Generate characterization tests for uncovered methods before refactoring.
Use `characterization-test-generator` skill.

## Refactor Guard: 🔴 STOP

**Files**: ItemManager.swift, ItemRepository.swift
**Test coverage**: None (0 tests found)

**Action**: Do NOT refactor until characterization tests exist.
Refactoring without tests is like surgery without monitoring —
you won't know if you killed the patient.

Run `characterization-test-generator` on:
1. ItemManager (7 public methods)
2. ItemRepository (5 public methods)

Then re-run this guard.

# Run all tests
xcodebuild test -scheme YourApp

# Check specifically for regressions
xcodebuild test -scheme YourApp \
  -only-testing "YourAppTests/ItemManagerCharacterizationTests"

## Refactor Guard Report

**Scope**: [Files/classes to be refactored]
**Verdict**: ✅ PROCEED / ⚠️ NEEDS TESTS / 🔴 STOP

### Coverage Summary
| Class | Public Methods | Tests | Coverage | Verdict |
|-------|---------------|-------|----------|---------|
| ItemManager | 9 | 12 | 89% | ✅ |
| ItemRepository | 5 | 2 | 40% | ⚠️ |

### Missing Coverage
- [ ] `ItemRepository.sync()` — needs characterization test
- [ ] Error path for `ItemRepository.delete()` — untested

### Recommendations
1. [Action item]
2. [Action item]