prutill/src/delayedPromise.spec.ts

Environment-agnostic production-ready promise utility library for managing promise stacks and race conditions. Supports Node.js, Deno, and browsers.

import DelayedPromise from "./delayedPromise";

describe("DelayedPromise provides a Promise object what resolve after timeout", () => {
	beforeAll(() => {
		jest.useFakeTimers();
	});

	afterAll(() => {
		jest.useRealTimers();
	});

	it("should to by resolved after expired time", async () => {
		const resolvedValue = jest.fn();

		const promise = new DelayedPromise(500).then(r => resolvedValue(r));

		jest.runAllTimers();
		await promise;

		expect(resolvedValue).toHaveBeenCalledTimes(1);
		expect(resolvedValue).toHaveBeenCalledWith(undefined);
	});

	it("allows to pass through value", async () => {
		const resolvedValue = jest.fn();

		const promise = new DelayedPromise(500, "Hello").then(r => resolvedValue(r));

		jest.runAllTimers();
		await promise;

		expect(resolvedValue).toHaveBeenCalledTimes(1);
		expect(resolvedValue).toHaveBeenCalledWith("Hello");
	});

	it("should resolve immediately with default timeout", async () => {
		const resolvedValue = jest.fn();

		const promise = new DelayedPromise().then(r => resolvedValue(r));

		jest.runAllTimers();
		await promise;

		expect(resolvedValue).toHaveBeenCalledTimes(1);
		expect(resolvedValue).toHaveBeenCalledWith(undefined);
	});
});