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Migrate to Shoehorn

Swap risky `as` type casts in TypeScript tests for type-safe shoehorn helpers.

Source Download skill
Repository
mattpocock/skills
Stars
309,658
Licence
MIT
Files
2 files

What it does

When you ask, the agent rewrites TypeScript test files that use `as` type casts to fake test data, replacing them with helpers from the @total-typescript/shoehorn library. Those helpers let a test pass partial objects while keeping the type checker useful, and they offer a way to pass deliberately wrong data for error testing. The agent can also install the library, find the casts with a search command, and run a type check afterwards.

Great for

  • TypeScript developers whose test files are full of `as Type` casts
  • Teams with large request or config types where tests only need a few properties
  • Anyone who wants a cleaner way to pass intentionally invalid data in tests

Skip it if

  • Production code: the skill itself says shoehorn is for test code only, since it bypasses type checking
  • Projects not using TypeScript, where the migration has no meaning
  • Codebases that rely on the type checker to catch missing fields in tests, because fromPartial relaxes that check

Try asking

  • “Migrate the `as Request` casts in my test files to shoehorn's fromPartial”
  • “Replace my `as unknown as User` casts in the spec files with fromAny”
  • “Install shoehorn and find all the `as` assertions in my .test.ts files”
Step-by-step guide: how to use Migrate to ShoehornInstall, first run, examples, tips and FAQs

Install in 3 steps

  1. 1

    Download the skill

    The ZIP contains the 2 original files, the MIT licence and an attribution note.

    migrate-to-shoehorn.zip
  2. 2

    Add it to your agent

    Claude Code (all projects)

    mkdir -p ~/.claude/skills && unzip migrate-to-shoehorn.zip -d ~/.claude/skills/

    Claude Code / Agent SDK (this project only)

    mkdir -p .claude/skills && unzip migrate-to-shoehorn.zip -d .claude/skills/

    Claude apps (web/desktop): Settings → Capabilities → Skills → Upload skill, and choose the ZIP.

  3. 3

    Ask for the task

    No special command needed — the agent reads the skill's description and loads it when your request matches. Try one of the prompts above.

Get better results

  • Ask the agent to run your type check after migration, since the skill's final step relies on it to verify the changes.
  • Review each replacement: fromPartial and fromAny silence checks that `as` also silenced, so the tests lose some safety.
  • Point the agent at specific folders if the project has many test files, to keep the diff reviewable.

What's inside

  • agents/openai.yaml
  • SKILL.md

Redistributed unmodified from mattpocock/skills under the MIT licence. The assessment was drafted with AI from the skill's files on 2026-10-29. Skills can instruct your agent to run code — read SKILL.md and any scripts before installing.