JoshHeaps.Net/tests/holdem/loadFailure.test.js

// What happens when the saved table can't be read.
//
// An unreadable save can only become an empty table. What it must not do is become
// one silently and then get written over by the first edit.
const test = require("node:test");
const assert = require("node:assert");
const { HoldemState } = require("./load");

function withStored(value, { readOnly = false } = {}) {
    const store = new Map();
    if (value !== undefined) store.set(HoldemState.STORAGE_KEY, value);
    globalThis.localStorage = {
        getItem: key => (store.has(key) ? store.get(key) : null),
        setItem(key, val) {
            if (readOnly) throw new Error("QuotaExceededError");
            store.set(key, val);
        },
        removeItem: key => store.delete(key),
    };
    return store;
}

test.beforeEach(() => {
    HoldemState.loadFailed = false;
    HoldemState.onLoadFailed = null;
});

test.after(() => {
    delete globalThis.localStorage;
    HoldemState.loadFailed = false;
    HoldemState.onLoadFailed = null;
});

test("nothing stored is a new table, not a failure", () => {
    withStored(undefined);
    const state = HoldemState.load();

    assert.equal(HoldemState.loadFailed, false);
    assert.ok(Array.isArray(state.seats));
});

test("a good save loads and reports nothing", () => {
    const store = withStored(undefined);
    const original = HoldemState.createDefault();
    original.handNumber = 34;
    HoldemState.save(original);

    const state = HoldemState.load();
    assert.equal(HoldemState.loadFailed, false);
    assert.equal(state.handNumber, 34);
    assert.equal(store.has(HoldemState.RECOVERY_KEY), false);
});

test("a truncated save is reported rather than silently becoming an empty table", () => {
    const good = JSON.stringify(HoldemState.createDefault());
    withStored(good.slice(0, Math.floor(good.length * 0.7)));

    const state = HoldemState.load();
    assert.equal(HoldemState.loadFailed, true);
    assert.ok(Array.isArray(state.seats), "it still hands back a usable table");
});

test("valid JSON of the wrong shape counts as unreadable too", () => {
    withStored(JSON.stringify({ hello: "world" }));

    HoldemState.load();
    assert.equal(HoldemState.loadFailed, true);
});

test("the unreadable copy is kept instead of being written over", () => {
    // This is the half that matters: whatever a person could have picked out of the
    // raw JSON used to be gone the moment the dealer touched a seat.
    const broken = '{"seats":[{"name":"Ann","stack":250},{"name":"Ben"';
    const store = withStored(broken);

    HoldemState.load();

    assert.equal(store.get(HoldemState.RECOVERY_KEY), broken);
});

test("a later save doesn't touch the copy that was set aside", () => {
    const broken = '{"seats":[{"name":"Ann"';
    const store = withStored(broken);

    const state = HoldemState.load();
    state.handNumber = 2;
    HoldemState.save(state);

    assert.equal(store.get(HoldemState.RECOVERY_KEY), broken);
    assert.notEqual(store.get(HoldemState.STORAGE_KEY), broken);
});

test("the listener fires once, not on every read", () => {
    withStored("{not json");
    let told = 0;
    HoldemState.onLoadFailed = () => { told++; };

    HoldemState.load();
    HoldemState.load();
    HoldemState.load();

    assert.equal(told, 1);
});

test("no room to keep the copy is not a crash", () => {
    // Storage that refuses writes is exactly the storage most likely to hand back a
    // half-written value in the first place.
    withStored("{not json", { readOnly: true });

    let state;
    assert.doesNotThrow(() => { state = HoldemState.load(); });
    assert.ok(Array.isArray(state.seats));
    assert.equal(HoldemState.loadFailed, true);
});