test-kit

Tier 0. No titan dependencies.

npm install --save-dev @titan-design/test-kit

Status: unpublished. The first version is published by hand.

The problem it solves

A test often needs a value of a wide interface when the code under test reads two of its fields. Writing every field is noise, so tests reached for { path } as unknown as ChangedFile. That double cast also hides real type errors, such as a misspelled field, and titan/no-chained-type-assertions now reports it. partialFake<T>() keeps the one reviewed cast inside the helper and type-checks the fields a test does write.

When to reach for it

• A test needs a T and fakes only some of its fields.
• A test probes how code handles a missing field: leave that field out.

For a fake with behaviour, such as an in-memory GitHub, use the owning package's fake (fakeGitHub() in github).

Public API

Export	What it does
partialFake<T>(fields?)	returns fields typed as T; fields is Partial<T>, so a field T does not declare fails the typecheck

Example

import { partialFake } from "@titan-design/test-kit";

interface Client {
  name: string;
  send(body: string): Promise<number>;
}

const client = partialFake<Client>({ send: async (body) => body.length });
await client.send("four"); // 4

What it deliberately does not do

• It does not throw when the code under test reads a field the test left out. Tests that probe missing input rely on reading undefined.
• It does not deep-fake nested objects. Nest a second partialFake call for a nested field.

Gotchas

• T claims every field exists. A field left out reads as undefined, so a test that forgets a field the code needs fails with a TypeError far from the fake.

Where it came from

New, for the anti-slop cast rules: it replaces as unknown as T fakes in test files.