Migrate to Shoehorn by @mattpocock · Skillet

Migrate to Shoehorn

Migrate test files from `as` type assertions to @total-typescript/shoehorn. Use when user mentions shoehorn, wants to replace `as` in tests, or needs partial test data.

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SKILL.md

migrate-to-shoehorn

Migrate test files from `as` type assertions to @total-typescript/shoehorn. Use when user mentions shoehorn, wants to replace `as` in tests, or needs partial test data.

Migrate to Shoehorn

Why shoehorn?

shoehorn lets you pass partial data in tests while keeping TypeScript happy. It replaces as assertions with type-safe alternatives.

Test code only. Never use shoehorn in production code.

Problems with as in tests:

Trained not to use it
Must manually specify target type
Double-as (as unknown as Type) for intentionally wrong data

Install

npm i @total-typescript/shoehorn

Migration patterns

Large objects with few needed properties

Before:

type  = {
  : { :  };
  : <, >;
  : <, >;
  
};

(,  {
  
  ({
    : { :  },
    : {},
    : {},
    
  });
});

2 files · 3 KB3 KB

Version history

import { fromPartial } from "@total-typescript/shoehorn";

it("gets user by id", () => {
  getUser(
    fromPartial({
      body: { id: "123" },
    }),
  );
});

getUser({ body: { id: "123" } } as Request);

import { fromPartial } from "@total-typescript/shoehorn";

getUser(fromPartial({ body: { id: "123" } }));

getUser({ body: { id: 123 } } as unknown as Request); // wrong type on purpose

import { fromAny } from "@total-typescript/shoehorn";

getUser(fromAny({ body: { id: 123 } }));

Function	Use case
`fromPartial()`	Pass partial data that still type-checks
`fromAny()`	Pass intentionally wrong data (keeps autocomplete)
`fromExact()`	Force full object (swap with fromPartial later)

Migrate to Shoehorn

Migrate to Shoehorn

Why shoehorn?

Install

Migration patterns

Large objects with few needed properties

`as Type` → `fromPartial()`

`as unknown as Type` → `fromAny()`

When to use each

Workflow

Migrate to Shoehorn

Why shoehorn?

Install

Migration patterns

Large objects with few needed properties

as Type → fromPartial()

as unknown as Type → fromAny()

When to use each

Workflow

`as Type` → `fromPartial()`

`as unknown as Type` → `fromAny()`