gh-jwplatta-prompt-library-claude-plugins-rubyist/skills/ruby-test-analyzer/SKILL.md

Ruby Test Analyzer Skill

Intelligently analyze RSpec test failures and provide actionable debugging guidance.

When to Activate

This skill activates when:

• RSpec tests fail
• User runs test commands
• User asks about test failures or debugging
• Working with test files

Core Capabilities

1. Failure Pattern Recognition

Automatically identify common failure patterns:

NoMethodError Patterns:

• Nil object errors → Check object initialization
• Missing method → Check for typos or missing implementation
• Wrong receiver → Check factory setup or test doubles

Expectation Failures:

• Off-by-one errors → Check loop boundaries
• Wrong values → Check business logic implementation
• Type mismatches → Check data transformation

Database/State Issues:

• Transactional rollback problems
• Factory/fixture conflicts
• Test interdependencies

2. Provide Debugging Steps

For each failure, suggest:

1. Immediate Checks:

   • Verify object is not nil
   • Check method spelling
   • Confirm proper setup in before blocks

2. Investigation Steps:

   • Add puts or binding.pry at strategic points
   • Check factory definitions
   • Verify database state

3. Likely Fixes:

   • Code examples showing the fix
   • References to related files
   • Design improvements to prevent recurrence

3. Test Quality Analysis

Evaluate test quality:

Good Signs:

• Clear describe/context structure
• Single responsibility per test
• Proper use of let/let!/before
• Descriptive test names
• Good isolation

Warning Signs:

• Tests with multiple expectations
• Tests depending on execution order
• Overuse of let! (eager evaluation)
• Brittle tests (too coupled to implementation)
• Missing edge cases

4. Suggest Missing Tests

Identify untested scenarios:

• Edge cases
• Error conditions
• Boundary values
• Integration points
• State transitions

Example Analysis

Failure Detected:

Failure/Error: expect(user.full_name).to eq("John Doe")
  expected: "John Doe"
       got: "John"

Analysis Response:

Failure: User#full_name incomplete

• Location: spec/user_spec.rb:23
• Error Type: Expectation mismatch

Immediate Cause: The full_name method is only returning the first name.

Investigation Steps:

1. Check the implementation at lib/user.rb:15

   # Current implementation (likely):
   def full_name
     first_name
   end
   

2. Verify test data:

   # Check that your factory/test setup has both names
   user = User.new(first_name: "John", last_name: "Doe")
   

Suggested Fix:

# lib/user.rb:15
def full_name
  [first_name, last_name].compact.join(' ')
end

Additional Considerations:

• Handle nil values gracefully (using compact)
• Consider edge cases: missing last name, middle names
• Add test for user with only first name

Suggested Additional Tests:

context 'when last_name is missing' do
  it 'returns only first_name' do
    user = User.new(first_name: "John", last_name: nil)
    expect(user.full_name).to eq("John")
  end
end

Performance Analysis

When tests are slow:

Identify Bottlenecks:

1. Run with profiling: bundle exec rspec --profile
2. Find slowest examples
3. Categorize delays:
   • Database operations
   • External service calls
   • Complex computations
   • Factory creation

Optimization Suggestions:

Database-Heavy Tests:

• Use build_stubbed instead of create
• Use let instead of let! where possible
• Consider using transactions or database_cleaner strategies

External Services:

• Stub external API calls
• Use VCR for HTTP interactions
• Mock time-consuming operations

Factory Optimization:

• Minimize associated records
• Use traits for specific scenarios
• Consider using build instead of create

Interactive Debugging

Offer to:

1. Add debugging output to specific lines
2. Insert binding.pry at failure point
3. Show related code context
4. Run specific tests in isolation
5. Check factory definitions
6. Verify test data setup

Test Coverage Suggestions

Suggest tests for:

• Happy path: Normal expected usage
• Edge cases: Boundary conditions
• Error cases: Invalid inputs
• Null cases: Nil/empty values
• Integration: Cross-object interactions

Guidelines

• Focus on actionable next steps
• Provide specific line numbers and file paths
• Show concrete code examples
• Explain the "why" behind failures
• Suggest preventive measures
• Balance speed of fix with quality of solution