acc-analyze-test-coverage

name	acc-analyze-test-coverage
description	Analyzes PHP codebase for test coverage gaps. Detects untested classes, methods, branches, exception paths, and edge cases. Provides actionable recommendations.

Test Coverage Analysis

Analyzes PHP codebase to identify untested code and coverage gaps.

Detection Patterns

1. Classes Without Tests

# Find all PHP classes in src/
Glob: src/**/*.php

# Find all test files
Glob: tests/**/*Test.php

# Compare: class Foo in src/ should have FooTest in tests/

Pattern Matching:

src/Domain/User/User.php → tests/Unit/Domain/User/UserTest.php
src/Application/PlaceOrder/PlaceOrderHandler.php → tests/Unit/Application/PlaceOrder/PlaceOrderHandlerTest.php

2. Methods Without Tests

// For each public method in class
Grep: "public function [a-z]" --glob "src/**/*.php"

// Check if test method exists
Grep: "test_methodName" --glob "tests/**/*Test.php"

Detection Logic:

Class: Order
├── confirm() → test_confirm_* exists? ✅/❌
├── cancel() → test_cancel_* exists? ✅/❌
├── ship() → test_ship_* exists? ✅/❌
└── addItem() → test_addItem_* / test_add_item_* exists? ✅/❌

3. Branches Not Covered

If/Else Branches:

// Source code
public function process(Order $order): void
{
    if ($order->isPending()) {     // Branch 1: pending
        $this->processPending($order);
    } elseif ($order->isConfirmed()) { // Branch 2: confirmed
        $this->processConfirmed($order);
    } else {                       // Branch 3: other
        throw new InvalidStateException();
    }
}

// Required tests:
// - test_process_when_pending_*
// - test_process_when_confirmed_*
// - test_process_when_other_throws_exception

Switch Statements:

// Source code
match ($status) {
    'pending' => $this->handlePending(),
    'confirmed' => $this->handleConfirmed(),
    'shipped' => $this->handleShipped(),
    default => throw new UnexpectedValueException(),
};

// Required tests: one per case + default

4. Exception Paths

// Detect throw statements
Grep: "throw new" --glob "src/**/*.php"

// Each throw should have corresponding test with expectException

Example:

// Source
public function withdraw(Money $amount): void
{
    if ($amount->greaterThan($this->balance)) {
        throw new InsufficientFundsException();  // Line 15
    }
}

// Required test
public function test_withdraw_throws_for_insufficient_funds(): void
{
    $this->expectException(InsufficientFundsException::class);
    // ...
}

5. Edge Cases

Type	Values to Test	Detection
Null	null input	Parameters without type hint or nullable
Empty	[], '', 0	Collection/string/numeric parameters
Boundary	min, max, min-1, max+1	Constants, validation limits
Unicode	'émoji 🎉'	String parameters
Concurrent	Race conditions	Shared state, repositories

Detection Patterns:

// Nullable parameters
Grep: "\?[A-Z]" --glob "src/**/*.php"  // ?Type
Grep: "null\|" --glob "src/**/*.php"   // Type|null

// Collections
Grep: "array \$" --glob "src/**/*.php"
Grep: "iterable" --glob "src/**/*.php"

// Numeric limits
Grep: "const MAX_" --glob "src/**/*.php"
Grep: "const MIN_" --glob "src/**/*.php"

Analysis Process

Phase 1: Inventory

1. List all production classes:

   Glob: src/**/*.php
   

2. List all test classes:

   Glob: tests/**/*Test.php
   

3. Build mapping:

   ProductionClass → [TestClass, TestClass]
   

Phase 2: Class Coverage

For each production class:

1. Check if corresponding test exists
2. Calculate: covered_classes / total_classes * 100

Phase 3: Method Coverage

For each public method:

1. Extract method names from production code
2. Search for test_{method} patterns in tests
3. Calculate: tested_methods / total_methods * 100

Phase 4: Branch Coverage

For each conditional:

1. Count branches (if/elseif/else, match cases)
2. Search for tests covering each branch
3. Report uncovered branches

Phase 5: Edge Cases

1. Identify nullable/optional parameters
2. Identify collections
3. Identify numeric limits
4. Check if edge case tests exist

Output Format

# Test Coverage Analysis Report

## Summary

| Metric | Value | Target |
|--------|-------|--------|
| Class Coverage | 75% | 90% |
| Method Coverage | 60% | 80% |
| Branch Coverage | 45% | 70% |

## Untested Classes

| Class | Location | Priority |
|-------|----------|----------|
| `PaymentProcessor` | src/Domain/Payment/ | High |
| `EmailNotifier` | src/Infrastructure/ | Medium |

## Untested Methods

| Class | Method | Reason |
|-------|--------|--------|
| `Order` | `splitShipment()` | No test found |
| `User` | `resetPassword()` | Only happy path tested |

## Uncovered Branches

| File | Line | Branch | Missing Test |
|------|------|--------|--------------|
| Order.php | 45 | else (cancelled) | test_ship_when_cancelled |
| User.php | 23 | null check | test_with_null_email |

## Missing Edge Cases

| Class | Method | Edge Case |
|-------|--------|-----------|
| `Cart` | `addItem()` | Empty cart, max items |
| `Money` | `add()` | Zero amount, overflow |

## Action Items

### Critical (Must Have)
1. Add `PaymentProcessorTest` — handles money
2. Add `test_order_ship_when_cancelled` — business rule

### High Priority
1. Add null checks for `User::resetPassword()`
2. Add boundary tests for `Cart::addItem()`

### Recommended Skills

| Gap | Skill | Action |
|-----|-------|--------|
| Missing unit test | `acc-create-unit-test` | Generate test class |
| Missing integration test | `acc-create-integration-test` | Generate DB test |
| Need test data | `acc-create-test-builder` | Generate builder |

Severity Levels

Level	Coverage	Action
Critical	<50%	Immediate attention
Warning	50-70%	Prioritize improvement
Good	70-90%	Monitor and maintain
Excellent	>90%	Focus on edge cases

Integration with Generator

After analysis, recommend using:

• acc-create-unit-test — for missing unit tests
• acc-create-integration-test — for missing integration tests
• acc-create-test-builder — for complex test data
• acc-create-mock-repository — for repository tests