result-guard-vitest

Vitest matchers for asserting on neverthrow Result/ResultAsync values.

Install

npm install -D result-guard-vitest

Add it to your Vitest config:

// vitest.config.ts
export default defineConfig({
  test: {
    setupFiles: ["result-guard-vitest"],
  },
});

Usage

import { guard } from "result-guard";

const guardedFetch = guard(fetchUser);

test("returns Ok for a valid id", async () => {
  const result = await guardedFetch("123");
  expect(result).toBeOk();
  expect(result).toMatchOk({ id: "123", name: "Alice" });
});

test("returns Err for an empty id", async () => {
  const result = await guardedFetch("");
  expect(result).toBeErr();
});

toMatchOk/toMatchErr support the same partial matchers as toMatchObject — expect.objectContaining(...) works fine.

If you pass an un-awaited ResultAsync directly, the matchers give you a specific error telling you to await it first, instead of a confusing generic assertion failure.

License

MIT