Test Coverage Analyzer

A skill for analyzing test coverage in NestJS projects, identifying files without tests, and creating task lists for missing tests.

Features

• •Find Untested Files: Scan the codebase to find TypeScript files without corresponding .spec.ts files
• •Check Test Coverage: Analyze which modules, services, controllers, and utilities lack tests
• •Generate Task Lists: Create organized todo lists for writing missing tests
• •Coverage Report: Provide summary statistics of test coverage

Usage

Tell Claude:

"Analyze test coverage and create task list for missing tests"

or

"Find all files without unit tests"

or

"Check which files need unit tests in libs/ and apps/"

How It Works

1. File Discovery

The skill scans the following patterns:

• •apps/**/*.ts - Application files
• •libs/**/*.ts - Library files
• •Excludes: .spec.ts, .dto.ts, .interface.ts, .index.ts, main.ts

2. Test Mapping

For each source file, checks for:

• •*.service.ts → *.service.spec.ts
• •*.controller.ts → *.controller.spec.ts
• •*.module.ts → *.module.spec.ts
• •*.ts (utilities) → *.spec.ts

3. Priority Categories

Files are categorized by priority:

High Priority (Core business logic):

• •Services (*.service.ts)
• •Controllers (*.controller.ts)
• •Utility functions with business logic

Medium Priority (Infrastructure):

• •Modules (*.module.spec.ts)
• •Guards, Interceptors, Pipes

Low Priority (Typically not tested):

• •DTOs (use *.dto.spec.ts for validation tests only if complex)
• •Interface files
• •Index/barrel files
• •main.ts bootstrap file
• •Enum files
• •Constant files

4. Task List Generation

Creates a structured task list:

## Unit Test Tasks

### High Priority
- [ ] Write tests for libs/auth/src/password.service.ts
- [ ] Write tests for libs/users/src/users.controller.ts

### Medium Priority
- [ ] Write tests for libs/auth/src/auth.module.ts

Patterns

Finding Untested Files

# Find all TypeScript files in apps/
find apps/ -name "*.ts" ! -name "*.spec.ts" ! -name "*.dto.ts" ! -name "main.ts"

# Find all TypeScript files in libs/
find libs/ -name "*.ts" ! -name "*.spec.ts" ! -name "*.dto.ts"

# Check for missing test files
for file in $(find libs/ -name "*.ts" ! -name "*.spec.ts"); do
  spec="${file%.ts}.spec.ts"
  if [ ! -f "$spec" ]; then
    echo "$file missing test: $spec"
  fi
done

NestJS-Specific Patterns

Services: Always need tests

// my.service.ts → my.service.spec.ts
describe('MyService', () => {
  let service: MyService;
  // ... test implementation
});

Controllers: Always need tests

// my.controller.ts → my.controller.spec.ts
describe('MyController', () => {
  let controller: MyController;
  // ... test implementation
});

Modules: Optional but recommended

// my.module.ts → my.module.spec.ts
describe('MyModule', () => {
  it('should compile the module', async () => {
    // ... test implementation
  });
});

Examples

Example 1: Full Project Analysis

User: "Analyze test coverage for the entire project"

Claude:

1. •Scans apps/ and libs/ directories
2. •Identifies all .ts files
3. •Checks for corresponding .spec.ts files
4. •Creates task list grouped by priority
5. •Provides coverage statistics

Example 2: Library-Specific Analysis

User: "Check test coverage in libs/auth-utilities"

Claude:

1. •Scans only libs/auth-utilities/
2. •Lists files without tests
3. •Suggests test patterns based on file types

Example 3: Service Focus

User: "Find all services without unit tests"

Claude:

1. •Finds all *.service.ts files
2. •Checks for *.service.spec.ts files
3. •Creates task list for missing service tests

Output Format

Summary Report

Test Coverage Analysis for: /path/to/project

Summary:
- Total TypeScript files: 45
- Files with tests: 32 (71.1%)
- Files without tests: 13 (28.9%)

Breakdown by type:
- Services: 8/10 tested (80%)
- Controllers: 5/6 tested (83.3%)
- Modules: 3/8 tested (37.5%)
- Utilities: 16/21 tested (76.2%)

Files without tests (High Priority:
1. libs/auth-utilities/src/password.ts (utility - business logic)
2. libs/caching/src/caching.service.ts (service)
3. apps/api/src/users/users.controller.ts (controller)
...

Task List

## Unit Test Tasks

### High Priority (Core Business Logic)
- [ ] Write tests for libs/auth-utilities/src/password.ts
  - Test hashPassword() function
  - Test verifyPassword() function
  - Edge cases: empty passwords, special characters

- [ ] Write tests for libs/caching/src/caching.service.ts
  - Test get() method
  - Test set() method with TTL
  - Test del() method

### Medium Priority (Infrastructure)
- [ ] Write tests for libs/caching/src/caching.module.ts
  - Test module compilation
  - Test service loading

Coverage Goals

• •Services: 100% coverage required
• •Controllers: 100% coverage required
• •Modules: 100% coverage recommended
• •Utilities: 100% coverage if contains logic
• •DTOs: Only if complex validation logic

Special Cases

Files That Don't Need Tests

• •main.ts - Bootstrap file (use E2E tests instead)
• •*.interface.ts - Interface definitions
• •*.index.ts - Barrel exports
• •*.enum.ts - Enum definitions
• •*.constants.ts - Constant definitions
• •*.types.ts - Type definitions

Files with Conditional Testing

• •*.dto.ts - Test only if complex validation
• •*.guard.ts - Test if custom logic
• •*.pipe.ts - Test if transformation logic
• •*.interceptor.ts - Test if custom logic

Integration with Other Skills

Works best with:

• •nestjs-unit-testing - For writing the actual tests
• •nestjs-conventions - For following NestJS patterns
• •prisma-patterns - For testing Prisma-related code

Quick Commands

# Quick check - count files without tests
find libs apps -name "*.ts" ! -name "*.spec.ts" ! -name "*.dto.ts" ! -name "main.ts" | wc -l

# List files without tests
find libs apps -name "*.ts" ! -name "*.spec.ts" ! -name "*.dto.ts" ! -name "main.ts"

# Check specific library
find libs/auth-utilities -name "*.ts" ! -name "*.spec.ts"

# Find services without tests
find libs apps -name "*.service.ts" | while read f; do [ ! -f "${f%.ts}.spec.ts" ] && echo "$f"; done

Best Practices

1. •Run analysis regularly - After adding new features
2. •Review priority list - Focus on high-priority items first
3. •Use task lists - Track progress with TodoWrite
4. •Aim for 100% coverage - On business logic files
5. •Update task list - Mark items as completed

Notes

• •The skill uses file patterns to determine test requirements
• •Certain file types are excluded by default (DTOs, interfaces, etc.)
• •Priority is based on business logic importance
• •Task lists are organized for efficient workflow