Exhaustiveness Checking

What it does

This skill allows an AI agent to verify that a TypeScript switch statement or similar construct handles all possible cases of a discriminated union. It ensures no potential values are missed, preventing runtime errors and improving code reliability. The skill provides feedback on whether the exhaustive check passed or failed, highlighting any missing cases.

When to use it

• Code Review: Automatically assess TypeScript code for exhaustiveness in switch statements when reviewing pull requests.
• Refactoring: Identify potential issues during refactoring of existing TypeScript codebases that utilize discriminated unions.
• Learning/Debugging: Help developers understand and debug type errors related to incomplete pattern matching.
• Automated Testing: Integrate into CI/CD pipelines to ensure exhaustiveness checks are consistently enforced.

Key capabilities

• Analyzes switch statements with discriminated union types.
• Identifies missing cases in the switch statement.
• Provides feedback on whether the exhaustive check passed or failed.

Example prompts

• "Check if this TypeScript code is exhaustively handling all possible values of the 'Status' type." [followed by code]
• “Analyze this switch statement for completeness regarding the 'Shape' union.” [followed by code]
• "Can you verify that this switch block covers all cases in my 'Fruit' discriminated union?" [followed by code]

Tips & gotchas

This skill requires valid TypeScript code as input. It is most effective when dealing with explicit discriminated unions; implicit or complex union types might yield less accurate results.