migrate-to-shoehorn

Original：🇺🇸 English

Translated

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.

9installs

Sourcemattpocock/skills

Added on2026-02-19

NPX Install

npx skill4agent add mattpocock/skills migrate-to-shoehorn

SKILL.md Content

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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

bash

npm i @total-typescript/shoehorn

Migration patterns

Large objects with few needed properties

Before:

ts

type Request = {
  body: { id: string };
  headers: Record<string, string>;
  cookies: Record<string, string>;
  // ...20 more properties
};

it("gets user by id", () => {
  // Only care about body.id but must fake entire Request
  getUser({
    body: { id: "123" },
    headers: {},
    cookies: {},
    // ...fake all 20 properties
  });
});

After:

ts

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

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

as Type

→

fromPartial()

Before:

ts

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

After:

ts

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

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

as unknown as Type

→

fromAny()

Before:

ts

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

After:

ts

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

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

When to use each

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)

Workflow

Gather requirements - ask user:
- What test files have
```
as
```
  assertions causing problems?
- Are they dealing with large objects where only some properties matter?
- Do they need to pass intentionally wrong data for error testing?

Install and migrate:

Install:
```
npm i @total-typescript/shoehorn
```

Find test files with

as

assertions:

grep -r " as [A-Z]" --include="*.test.ts" --include="*.spec.ts"

Replace
```
as Type
```
with
```
fromPartial()
```
Replace
```
as unknown as Type
```
with
```
fromAny()
```
Add imports from
```
@total-typescript/shoehorn
```
Run type check to verify

migrate-to-shoehorn

NPX Install

Tags

SKILL.md Content

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