From mattpocock-skills
Migrates TypeScript test files from `as` type assertions to @total-typescript/shoehorn for type-safe partial test data without faking full objects.
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`shoehorn` lets you pass partial data in tests while keeping TypeScript happy. It replaces `as` assertions with type-safe alternatives.
Migrates TypeScript test files from 'as' type assertions to @total-typescript/shoehorn for type-safe partial and invalid test data. Use when replacing 'as' in tests or handling large objects.
Sets up Vitest testing by detecting project type (React, Node, Hono, Cloudflare Workers), generating config/tests/utilities, adding scripts, and migrating from Jest.
Guides migration from Jest to Bun's test runner including import updates, mock/spy/timer compatibility, snapshot testing, and jest.config.js to bunfig.toml conversion.
Share bugs, ideas, or general feedback.
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:
as unknown as Type) for intentionally wrong datanpm i @total-typescript/shoehorn
Before:
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:
import { fromPartial } from "@total-typescript/shoehorn";
it("gets user by id", () => {
getUser(
fromPartial({
body: { id: "123" },
}),
);
});
as Type → fromPartial()Before:
getUser({ body: { id: "123" } } as Request);
After:
import { fromPartial } from "@total-typescript/shoehorn";
getUser(fromPartial({ body: { id: "123" } }));
as unknown as Type → fromAny()Before:
getUser({ body: { id: 123 } } as unknown as Request); // wrong type on purpose
After:
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) |
Gather requirements - ask user:
as assertions causing problems?Install and migrate:
npm i @total-typescript/shoehornas assertions: grep -r " as [A-Z]" --include="*.test.ts" --include="*.spec.ts"as Type with fromPartial()as unknown as Type with fromAny()@total-typescript/shoehorn