mobx-utils/test/lazy-observable.js

"use strict"

const utils = require("../src/mobx-utils")
const mobx = require("mobx")

mobx.configure({ enforceActions: "observed" })

test("lazy observable should work", (done) => {
    let started = false
    const lo = utils.lazyObservable((sink) => {
        started = true
        setTimeout(() => sink(4), 50)
        setTimeout(() => sink(5), 100)
        setTimeout(() => sink(6), 150)
    }, 3)

    const values = []
    expect(started).toBe(false)

    lo.refresh()
    expect(started).toBe(false)

    mobx.autorun(() => values.push(lo.current()))

    expect(started).toBe(true)
    expect(values).toEqual([3])
    expect(lo.current()).toBe(3)

    setTimeout(() => {
        expect(lo.current()).toBe(6)
        expect(values).toEqual([3, 4, 5, 6])
        done()
    }, 200)
})

test("lazy observable refresh", (done) => {
    let started = 0
    let i = 10

    const lo = utils.lazyObservable(
        (sink) =>
            new Promise((resolve) => {
                started = started + 1
                resolve(i)
                i++
            }).then((value) => {
                sink(value)
            }),
        1
    )

    let values = []
    mobx.autorun(() => values.push(lo.current()))

    expect(started).toBe(1)
    expect(values).toEqual([1])
    expect(lo.current()).toBe(1)

    setTimeout(() => lo.refresh(), 50)

    setTimeout(() => {
        expect(started).toBe(2)
        expect(lo.current()).toBe(11)
        expect(values).toEqual([1, 10, 11])
        done()
    }, 200)
})

test("lazy observable reset", (done) => {
    const lo = utils.lazyObservable(
        (sink) =>
            new Promise((resolve) => {
                resolve(2)
            }).then((value) => {
                sink(value)
            }),
        1
    )

    lo.current()

    setTimeout(() => {
        expect(lo.current()).toBe(2)
    }, 50)

    setTimeout(() => lo.reset(), 150)

    setTimeout(() => {
        expect(lo.current()).toBe(1)
    }, 200)

    setTimeout(() => {
        expect(lo.current()).toBe(2)
        done()
    }, 250)
})

test("lazy observable pending", (done) => {
    const lo = utils.lazyObservable((sink) =>
        new Promise((resolve) => {
            setTimeout(resolve, 100)
        }).then(sink)
    )

    expect(lo.pending).toBeFalsy()

    lo.current()
    expect(lo.pending).toBeTruthy()

    setTimeout(() => {
        expect(lo.pending).toBeFalsy()
        done()
    }, 150)
})

test("lazy observable pending can be observed", async () => {
    const sleep = (ms) => new Promise((resolve) => setTimeout(resolve, ms))

    const lo = utils.lazyObservable((sink) => sleep(100).then(sink))

    const pendingValues = []

    mobx.autorun(() => pendingValues.push(lo.pending))

    lo.current()

    await sleep(150)

    expect(pendingValues).toEqual([false, true, false])
})