AutistMask/tests/trackedTokenBalances.test.js

// The balance of each token the user tracks is read with balanceOf through the
// RPC endpoint, for every address, and Blockscout's answer adds only the tokens
// the user has not tracked (https://git.eeqj.de/sneak/AutistMask/issues/669).
//
// The real refreshBalances() runs against a fake JSON-RPC node, answered
// through ethers' own request hook, and a fake Blockscout, answered through
// fetch().

const { AbiCoder, FetchRequest } = require("ethers");
const { refreshBalances } = require("../src/shared/balances");

const RPC_URL = "https://rpc.example.invalid";
const EXPLORER_URL = "https://explorer.example.invalid/api/v2";
const FIRST = "0x1111111111111111111111111111111111111111";
const SECOND = "0x2222222222222222222222222222222222222222";

// A token the user tracks, outside the bundled list, at 6 decimals.
const TOKEN = "0x7777777777777777777777777777777777777777";
const TRACKED = {
    address: TOKEN,
    symbol: "TRK",
    name: "Tracked Token",
    decimals: 6,
};

// USDC, from the bundled list, which the user does not track.
const USDC = "0xa0b86991c6218b36c1d19d4a2e9eb0ce3606eb48";
// Neither on the bundled list nor tracked.
const OTHER = "0x8888888888888888888888888888888888888888";

const ZERO_WORD = "0x" + "0".repeat(64);
const BALANCE_OF = "0x70a08231";

// What balanceOf answers, by token contract and then by holder. A pair that is
// not here makes balanceOf fail.
let holdings;
// What Blockscout answers for every address; null makes the request fail.
let explorerRows;
let logged;

// One JSON-RPC answer. A call that is not balanceOf is the ENS reverse lookup,
// answered with no resolver, so no name.
function reply(req) {
    const envelope = { jsonrpc: "2.0", id: req.id };
    if (req.method === "eth_getBalance") {
        return { ...envelope, result: "0x0" };
    }
    if (req.method !== "eth_call") {
        return {
            ...envelope,
            error: { code: -32601, message: "method not found" },
        };
    }
    const { to, data } = req.params[0];
    if (!data.startsWith(BALANCE_OF)) return { ...envelope, result: ZERO_WORD };
    const holder = "0x" + data.slice(-40);
    const amount = (holdings[to.toLowerCase()] || {})[holder];
    if (amount === undefined) {
        return {
            ...envelope,
            error: { code: -32000, message: "fixture: balanceOf failed" },
        };
    }
    return {
        ...envelope,
        result: AbiCoder.defaultAbiCoder().encode(["uint256"], [amount]),
    };
}

const realFetch = globalThis.fetch;

beforeEach(() => {
    holdings = {};
    explorerRows = null;
    logged = [];
    jest.spyOn(console, "error").mockImplementation((...args) => {
        logged.push(args.map(String).join(" "));
    });
    FetchRequest.registerGetUrl(async (req) => {
        const body = JSON.parse(Buffer.from(req.body).toString("utf8"));
        const answer = Array.isArray(body) ? body.map(reply) : reply(body);
        return {
            statusCode: 200,
            statusMessage: "OK",
            headers: { "content-type": "application/json" },
            body: Buffer.from(JSON.stringify(answer)),
        };
    });
    globalThis.fetch = jest.fn(async () => {
        if (explorerRows === null) throw new TypeError("Failed to fetch");
        return { ok: true, status: 200, json: async () => explorerRows };
    });
});

afterEach(() => {
    FetchRequest.registerGetUrl(FetchRequest.createGetUrlFunc());
    globalThis.fetch = realFetch;
    jest.restoreAllMocks();
});

// One Blockscout token-balances row.
function explorerRow(address, symbol, value, holders = "50000") {
    return {
        value: String(value),
        token: {
            type: "ERC-20",
            address_hash: address,
            symbol: symbol,
            name: symbol,
            decimals: "6",
            holders_count: holders,
        },
    };
}

// The row refreshBalances() writes for TOKEN from a balanceOf answer.
function trackedRow(balance) {
    return {
        address: TOKEN,
        name: "Tracked Token",
        symbol: "TRK",
        decimals: null,
        balance: balance,
        holders: null,
    };
}

async function refresh(addresses, trackedTokens) {
    await refreshBalances(
        [{ addresses }],
        RPC_URL,
        EXPLORER_URL,
        trackedTokens,
        "mainnet",
        new AbortController().signal,
    );
    return addresses;
}

test("with Blockscout failing, a tracked token's balance is read through the RPC endpoint for every address", async () => {
    holdings[TOKEN] = { [FIRST]: 1234500000n, [SECOND]: 1n };
    const [first, second] = await refresh(
        [
            { address: FIRST, tokenBalances: [] },
            { address: SECOND, tokenBalances: [] },
        ],
        [TRACKED],
    );
    expect(first.tokenBalances).toEqual([trackedRow("1234.5")]);
    // Exact, never cut: one base unit is not zero.
    expect(second.tokenBalances).toEqual([trackedRow("0.000001")]);
});

test("with Blockscout failing, the untracked rows from before stay", async () => {
    holdings[TOKEN] = { [FIRST]: 2000000n };
    const usdc = {
        address: USDC,
        name: "USD Coin",
        symbol: "USDC",
        decimals: 6,
        balance: "5.0",
        holders: 50000,
    };
    const [first] = await refresh(
        [{ address: FIRST, tokenBalances: [usdc] }],
        [TRACKED],
    );
    expect(first.tokenBalances).toEqual([trackedRow("2.0"), usdc]);
});

test("a tracked token Blockscout also reports shows the RPC figure, and an untracked one is admitted as before", async () => {
    holdings[TOKEN] = { [FIRST]: 2000000n };
    explorerRows = [
        explorerRow(TOKEN, "TRK", 9000000),
        explorerRow(USDC, "USDC", 5000000),
        // Too few holders, and neither on the bundled list nor tracked.
        explorerRow(OTHER, "SPAM", 5000000, "10"),
        // A known symbol from a contract it does not belong to.
        explorerRow(OTHER, "USDC", 5000000),
    ];
    const [first] = await refresh(
        [{ address: FIRST, tokenBalances: [] }],
        [TRACKED],
    );
    expect(first.tokenBalances).toEqual([
        trackedRow("2.0"),
        {
            address: USDC,
            name: "USDC",
            symbol: "USDC",
            decimals: 6,
            balance: "5.0",
            holders: 50000,
        },
    ]);
});

test("a failed balanceOf leaves the token's previous figure, and is logged", async () => {
    explorerRows = [];
    const before = trackedRow("7.0");
    const [first] = await refresh(
        [{ address: FIRST, tokenBalances: [before] }],
        [TRACKED],
    );
    expect(first.tokenBalances).toEqual([before]);
    expect(logged.some((line) => line.includes("token balance failed"))).toBe(
        true,
    );
});

test("a balance of zero read through the RPC endpoint replaces the previous figure", async () => {
    holdings[TOKEN] = { [FIRST]: 0n };
    const [first] = await refresh(
        [{ address: FIRST, tokenBalances: [trackedRow("7.0")] }],
        [TRACKED],
    );
    expect(first.tokenBalances).toEqual([]);
});

test("a tracked token whose scale nothing knows gets no quantity, not a zero", async () => {
    holdings[TOKEN] = { [FIRST]: 5n };
    const [first] = await refresh(
        [{ address: FIRST, tokenBalances: [] }],
        [{ ...TRACKED, decimals: null }],
    );
    expect(first.tokenBalances).toEqual([trackedRow(null)]);
});

test("a tracked token wearing a known symbol from another contract is not listed", async () => {
    holdings[OTHER] = { [FIRST]: 5000000n };
    const [first] = await refresh(
        [{ address: FIRST, tokenBalances: [] }],
        [{ address: OTHER, symbol: "USDC", name: "Fake", decimals: 6 }],
    );
    expect(first.tokenBalances).toEqual([]);
});