RBS Validate

Validate RBS type signatures against Ruby source code for correctness and completeness.

Instructions

1. Syntax Validation

First, validate RBS syntax using the rbs CLI:

# Validate all RBS files
rbs -I sig validate

# Parse and check specific file
rbs parse sig/lib/my_class.rbs

# Check with stdlib
rbs -I sig -r set -r json validate

2. Completeness Check

Compare RBS definitions against Ruby source:

For each Ruby class/module, verify:

• All public methods have signatures
• All attr_* declarations are typed
• Constants are defined
• Class methods are included
• Inheritance chain is correct

Report missing:

• Undefined methods
• Missing parameters
• Untyped instance variables

3. Type Consistency

Check that types make sense:

Method return types:

• Match actual return values
• Consider all code paths
• Include nil when applicable

Parameter types:

• Match how parameters are used
• Consider duck typing
• Verify optional/required status

Instance variable types:

• Match assignments throughout class
• Consider initialization order

4. Common Issues to Detect

# Missing nil handling
def find: (Integer id) -> User  # Should be User?

# Wrong parameter optionality
def create: (String name, String email)  # email might be optional

# Missing block signature
def each: () -> self  # Missing block parameter

# Incorrect generic types
def transform: (Array items) -> Array  # Should specify element types

5. Validation Report Format

Generate a report like:

## RBS Validation Report

### Syntax Errors
- `sig/lib/user.rbs:15`: Unexpected token 'end'

### Missing Definitions
- `lib/user.rb:User#validate` - No RBS signature found
- `lib/user.rb:User::ROLES` - Constant not typed

### Type Mismatches
- `User#find`: Returns `nil` but typed as `User`
- `User#initialize`: Parameter `age` is optional in code but required in RBS

### Warnings
- `User#process`: Consider using more specific type than `untyped`

### Summary
- Files checked: 5
- Errors: 2
- Warnings: 4
- Coverage: 85%

6. Integration with steep

If steep is available, use it for deeper validation:

# Run steep check
steep check

# Generate Steepfile if missing
steep init

Validation Workflow

1. Find all RBS files:

find sig -name "*.rbs"

2. Run syntax check:

rbs -I sig validate

3. Compare with Ruby source:

   • Read corresponding .rb file
   • Extract method signatures
   • Compare with RBS definitions

4. Generate report:

   • List all discrepancies
   • Suggest fixes
   • Calculate coverage metrics