sflow/src/toLatest.spec.ts

sflow is a powerful and highly-extensible library designed for processing and manipulating streams of data effortlessly. Inspired by the functional programming paradigm, it provides a rich set of utilities for transforming streams, including chunking, fil

import { sleep } from "./utils";
import sflow from "./index";
import { toLatests } from "./toLatest";

it("Get the latest value", async () => {
    const ret = toLatests(sflow([1, 2, 3])
        .forEach(async (e) => {
            await sleep(10);
        }))

    // wait for first emit
    expect(await ret.latest).toEqual(1);
    await sleep(100)
    expect(await ret.latest).toEqual(3);
});

it("works number", async () => {
    const ret = toLatests(sflow([1, 2, 3])
        .forEach(async (e) => {
            await sleep(10);
        }))

    // wait for first emit
    expect(await ret.latest).toEqual(1);

    expect(await ret.next).toEqual(2);
    expect(await ret.latest).toEqual(2);

    expect(await ret.next).toEqual(3);
    expect(await ret.latest).toEqual(3);

    expect(await ret.next).toEqual(undefined);

    expect(await ret.latest).toEqual(3);

    expect(await ret.next).toEqual(undefined);
});

it("works obj", async () => {
    const ret = toLatests(sflow([
        { b: 1 },
        { a: { b: { c: 2 } } },
        { c: 3 },
    ])
        .forEach(async () => {
            await sleep(10);
        }))

    // wait for first emit
    expect(await ret.latest).toEqual({ b: 1 });

    // @ts-ignore
    expect(await ret.next).toEqual({ a: { b: { c: 2 } } });
    expect(await ret.latest).toEqual({ a: { b: { c: 2 } } });

    expect(await ret.next).toEqual({ c: 3 });
    expect(await ret.latest).toEqual({ c: 3 });

    expect(await ret.next).toEqual(undefined);

    expect(await ret.next).toEqual(undefined);

    expect(await ret.latest).toEqual({ c: 3 });
});