Test Coverage Assistant

Test Coverage Assistant

Language: English | 繁體中文

Version: 1.1.1 Last Updated: 2026-01-30 Applicability: Claude Code Skills

Purpose

This skill helps evaluate and improve test completeness using the 8 dimensions framework, ensuring comprehensive test coverage for each feature.

Quick Reference

The 8 Dimensions

┌─────────────────────────────────────────────────────────────┐
│              Test Completeness = 8 Dimensions                │
├─────────────────────────────────────────────────────────────┤
│  1. Happy Path        Normal expected behavior              │
│  2. Boundary          Min/max values, limits                │
│  3. Error Handling    Invalid input, exceptions             │
│  4. Authorization     Role-based access control             │
│  5. State Changes     Before/after verification             │
│  6. Validation        Format, business rules                │
│  7. Integration       Real query verification               │
│  8. AI Generation     AI-generated test quality (NEW)       │
└─────────────────────────────────────────────────────────────┘

Dimension Summary Table

When to Apply Each Dimension

*Dimension 8 (AI Generation Quality) applies when tests are AI-generated

Test Design Checklist

Use this checklist for each feature:

Feature: ___________________

□ Happy Path
  □ Valid input produces expected success
  □ Correct data is returned/created
  □ Side effects occur as expected

□ Boundary Conditions
  □ Minimum valid value
  □ Maximum valid value
  □ Empty collection
  □ Single item collection
  □ Large collection (if applicable)

□ Error Handling
  □ Invalid input format
  □ Missing required fields
  □ Duplicate/conflict scenarios
  □ Not found scenarios
  □ External service failure (if applicable)

□ Authorization
  □ Each permitted role tested
  □ Each denied role tested
  □ Unauthenticated access tested
  □ Cross-boundary access tested

□ State Changes
  □ Initial state verified
  □ Final state verified
  □ All valid state transitions tested

□ Validation
  □ Format validation (email, phone, etc.)
  □ Business rule validation
  □ Cross-field validation

□ Integration (if UT uses wildcards)
  □ Query predicates verified
  □ Entity relationships verified
  □ Pagination verified
  □ Sorting/filtering verified

□ AI Generation Quality (if AI-generated)
  □ Tests verify meaningful behavior
  □ Assertions are specific (not just "not null")
  □ Tests are independent and self-contained
  □ Mutation score > 80% (if evaluated)

Detailed Guidelines

For complete standards, see:

• Test Completeness Dimensions
• Testing Standards

AI-Optimized Format (Token-Efficient)

For AI assistants, use the YAML format files for reduced token usage:

• Base standard: ai/standards/test-completeness-dimensions.ai.yaml

Examples

1. Happy Path

[Fact]
public async Task CreateUser_WithValidData_ReturnsSuccess()
{
    // Arrange
    var request = new CreateUserRequest
    {
        Username = "newuser",
        Email = "user@example.com"
    };

    // Act
    var result = await _service.CreateUserAsync(request);

    // Assert
    result.Success.Should().BeTrue();
    result.Data.Username.Should().Be("newuser");
}

2. Boundary

[Theory]
[InlineData(0, false)]      // Below minimum
[InlineData(1, true)]       // Minimum valid
[InlineData(100, true)]     // Maximum valid
[InlineData(101, false)]    // Above maximum
public void ValidateQuantity_BoundaryValues_ReturnsExpected(
    int quantity, bool expected)
{
    var result = _validator.IsValidQuantity(quantity);
    result.Should().Be(expected);
}

4. Authorization

[Fact]
public async Task DeleteUser_AsAdmin_Succeeds()
{
    var adminContext = CreateContext(role: "Admin");
    var result = await _service.DeleteUserAsync(userId, adminContext);
    result.Success.Should().BeTrue();
}

[Fact]
public async Task DeleteUser_AsMember_ReturnsForbidden()
{
    var memberContext = CreateContext(role: "Member");
    var result = await _service.DeleteUserAsync(userId, memberContext);
    result.ErrorCode.Should().Be("FORBIDDEN");
}

5. State Changes

[Fact]
public async Task DisableUser_UpdatesStateCorrectly()
{
    // Arrange
    var user = await CreateEnabledUser();
    user.IsEnabled.Should().BeTrue();  // Verify initial state

    // Act
    await _service.DisableUserAsync(user.Id);

    // Assert
    var updatedUser = await _repository.GetByIdAsync(user.Id);
    updatedUser.IsEnabled.Should().BeFalse();  // Verify final state
}

Authorization Matrix Template

Create a matrix for each feature:

Each cell should have a corresponding test case.

Anti-Patterns to Avoid

• ❌ Testing only happy path
• ❌ Missing authorization tests for multi-role systems
• ❌ Not verifying state changes
• ❌ Using wildcards in UT without corresponding IT
• ❌ Same values for ID and business identifier in test data
• ❌ Testing implementation details instead of behavior
• ❌ Accepting AI-generated tests without review
• ❌ Assuming high line coverage means effective tests

Configuration Detection

This skill supports project-specific configuration.

Detection Order

1. Check CONTRIBUTING.md for "Testing Standards" section
2. Check for existing test patterns in the codebase
3. If not found, default to all 8 dimensions (dimension 8 only when tests are AI-generated)

First-Time Setup

If no configuration found:

1. Suggest: "This project hasn't configured test completeness requirements. Would you like to customize which dimensions are required?"
2. Suggest documenting in CONTRIBUTING.md:

## Test Completeness

We use the 8 Dimensions framework for test coverage.

### Required Dimensions by Feature Type
- API endpoints: All 8 dimensions (8 only when AI-generated)
- Utility functions: Dimensions 1, 2, 3, 6, 8*
- Background jobs: Dimensions 1, 3, 5, 8*

*Dimension 8 applies when tests are AI-generated

Related Standards

• Test Completeness Dimensions
• Testing Standards
• Testing Guide

Version History

License

This skill is released under CC BY 4.0.

Source: universal-dev-standards