import { waitForever } from "./wait.js";

describe("waitForever", () => {

it("creates an unref'ed interval and returns a pending promise", () => {

it("keeps the event loop alive (ref'd interval) and returns a pending promise", () => {

const unref = vi.fn();

const interval = { unref } as unknown as ReturnType<typeof setInterval>;

const setIntervalSpy = vi.spyOn(global, "setInterval").mockReturnValue(interval);

const [callback, delay] = setIntervalSpy.mock.calls[0] ?? [];

expect(typeof callback).toBe("function");

expect(delay).toBe(1_000_000);

expect(unref).toHaveBeenCalledTimes(1);

// Regression guard for the previous `.unref()` bug: an unref'd interval

// does NOT keep the event loop alive, so `await waitForever()` would

// exit immediately with code 13 ("unsettled top-level await"). The

// function must NOT unref the interval.

expect(unref).not.toHaveBeenCalled();

expect(promise).toBeInstanceOf(Promise);

} finally {

setIntervalSpy.mockRestore();