vitest/prefer-mock-promise-shorthand

mockReturnValue(Promise.resolve(user)) and mockImplementation(() => Promise.resolve(user)) do the same thing as mockResolvedValue(user), with more code. The same goes for Promise.reject() and mockRejectedValue(), and for the Once version of each method.

--fix rewrites the call.

Configure

Off by default. To turn it on:

[lint.rules]
"vitest/prefer-mock-promise-shorthand" = "error" # or "warn"

Examples

Reported:

import { vi } from "vitest";

const fetchUser = vi.fn().mockReturnValue(Promise.resolve({ name: "Ada" }));
const saveUser = vi.fn().mockImplementationOnce(() => Promise.reject(new Error("offline")));

Not reported:

import { vi } from "vitest";

const fetchUser = vi.fn().mockResolvedValue({ name: "Ada" });
const saveUser = vi.fn().mockRejectedValueOnce(new Error("offline"));

An implementation that takes parameters is allowed, because its result can depend on them:

import { vi } from "vitest";

const fetchUser = vi.fn().mockImplementation((id: number) => Promise.resolve({ id }));