AutistMask/tests/approvalAmount.test.js

// The quantity the dApp approval screen shows for a decoded ERC-20 call.
//
// The screen's amount line is the only place a user sees how much a page is
// asking for, and it is decoded from calldata, which carries base units and
// no scale. Issue #306: decodeCalldata read decimals from the bundled token
// list alone and fell back to 18, so a `transfer` of 5000000000 units of a
// 6-decimal token — 5,000 tokens — was displayed as `0.0000` and confirmed.
//
// What is asserted here is that the scale is found wherever the wallet
// already has it, and that where it is nowhere at all no formatted number is
// produced: the amount line has to say base units and say the scale is
// unknown, because a wrong quantity that reads as zero is worse than an
// unwieldy correct one.

globalThis.chrome = {
    storage: { local: { get: async () => ({}), set: async () => {} } },
};

const { Interface } = require("ethers");
const { ERC20_ABI } = require("../src/shared/constants");
const { state } = require("../src/shared/state");
const {
    resolveTokenDecimals,
    unknownDecimalsAmount,
} = require("../src/shared/approvalAmount");
const { decodeCalldata } = require("../src/popup/views/approval");

const iface = new Interface(ERC20_ABI);

// Outside the bundled list, as the great majority of ERC-20s are.
const NOVEL_TOKEN = "0xE2E0000000000000000000000000000000000E2e";
// In the bundled list, at 6 decimals.
const USDC = "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48";
const RECIPIENT = "0xC0FfEE0000000000000000000000000000c0fFEe";
const SPENDER = "0x1111111111111111111111111111111111111111";

// 5,000 units of a 6-decimal token, the amount from the issue.
const FIVE_THOUSAND_AT_SIX = 5000000000n;
const MAX_UINT256 = (1n << 256n) - 1n;

function transferData(amount) {
    return iface.encodeFunctionData("transfer", [RECIPIENT, amount]);
}

function approveData(amount) {
    return iface.encodeFunctionData("approve", [SPENDER, amount]);
}

// The Amount line as the approval screen renders it.
function amountLine(data, tokenAddress) {
    const decoded = decodeCalldata(data, tokenAddress);
    const detail = decoded.details.find((d) => d.label === "Amount");
    return detail.value;
}

// A wallet holding `token` with the decimals the block explorer reported,
// shaped as balances.js writes it onto state.
function walletsHolding(token, decimals) {
    return [
        {
            name: "Wallet 1",
            addresses: [
                {
                    address: "0x" + "a".repeat(40),
                    balance: "1.0",
                    tokenBalances: [
                        {
                            address: token,
                            symbol: "NOVEL",
                            decimals,
                            balance: "5000.0",
                        },
                    ],
                },
            ],
        },
    ];
}

beforeEach(() => {
    state.trackedTokens = [];
    state.wallets = [];
});

describe("resolveTokenDecimals", () => {
    test("prefers the bundled list", () => {
        state.trackedTokens = [{ address: USDC, symbol: "USDC", decimals: 2 }];
        expect(resolveTokenDecimals(USDC, state)).toBe(6);
    });

    test("reads a token the user tracks", () => {
        state.trackedTokens = [
            {
                address: NOVEL_TOKEN.toLowerCase(),
                symbol: "NOVEL",
                decimals: 6,
            },
        ];
        expect(resolveTokenDecimals(NOVEL_TOKEN, state)).toBe(6);
    });

    test("reads the decimals the explorer reported", () => {
        // Blockscout's copy arrives as a string.
        state.wallets = walletsHolding(NOVEL_TOKEN, "6");
        expect(resolveTokenDecimals(NOVEL_TOKEN, state)).toBe(6);
    });

    test("falls past a tracked entry whose decimals are unusable", () => {
        state.trackedTokens = [
            { address: NOVEL_TOKEN, symbol: "NOVEL", decimals: NaN },
        ];
        state.wallets = walletsHolding(NOVEL_TOKEN, 6);
        expect(resolveTokenDecimals(NOVEL_TOKEN, state)).toBe(6);
    });

    test("refuses a scale the explorer's own entries disagree about", () => {
        const wallets = walletsHolding(NOVEL_TOKEN, 6);
        wallets[0].addresses.push({
            address: "0x" + "b".repeat(40),
            balance: "0.0",
            tokenBalances: [
                { address: NOVEL_TOKEN, symbol: "NOVEL", decimals: 18 },
            ],
        });
        state.wallets = wallets;
        expect(resolveTokenDecimals(NOVEL_TOKEN, state)).toBeNull();
    });

    test("rejects values that are not a uint8", () => {
        for (const decimals of [-1, 256, 1.5, true, [], {}, null, "6.0", ""]) {
            state.trackedTokens = [{ address: NOVEL_TOKEN, decimals }];
            expect(resolveTokenDecimals(NOVEL_TOKEN, state)).toBeNull();
        }
    });

    test("is null when nothing knows the token", () => {
        expect(resolveTokenDecimals(NOVEL_TOKEN, state)).toBeNull();
    });
});

describe("decodeCalldata amount", () => {
    test("transfer of a tracked 6-decimal token shows the true quantity", () => {
        state.trackedTokens = [
            { address: NOVEL_TOKEN, symbol: "NOVEL", decimals: 6 },
        ];
        expect(
            amountLine(transferData(FIVE_THOUSAND_AT_SIX), NOVEL_TOKEN),
        ).toBe("5000.0000");
    });

    test("transfer priced off the explorer's decimals shows the true quantity", () => {
        state.wallets = walletsHolding(NOVEL_TOKEN, "6");
        expect(
            amountLine(transferData(FIVE_THOUSAND_AT_SIX), NOVEL_TOKEN),
        ).toBe("5000.0000");
    });

    test("transfer of an unknown-decimals token shows base units, not a number", () => {
        const line = amountLine(
            transferData(FIVE_THOUSAND_AT_SIX),
            NOVEL_TOKEN,
        );
        expect(line).toBe("5000000000 base units (decimals unknown)");
        expect(line).toBe(unknownDecimalsAmount(FIVE_THOUSAND_AT_SIX));
        // The defect: any rendering that reads as a token quantity, and above
        // all one that reads as zero.
        expect(line).not.toMatch(/0\.0000/);
    });

    test("approve of a tracked 6-decimal token shows the true quantity", () => {
        state.trackedTokens = [
            { address: NOVEL_TOKEN, symbol: "NOVEL", decimals: 6 },
        ];
        expect(amountLine(approveData(FIVE_THOUSAND_AT_SIX), NOVEL_TOKEN)).toBe(
            "5000.0000",
        );
    });

    test("approve of an unknown-decimals token shows base units, not a number", () => {
        const line = amountLine(approveData(FIVE_THOUSAND_AT_SIX), NOVEL_TOKEN);
        expect(line).toBe("5000000000 base units (decimals unknown)");
        expect(line).not.toMatch(/0\.0000/);
    });

    test("an unbounded allowance is still named, with or without a scale", () => {
        expect(amountLine(approveData(MAX_UINT256), NOVEL_TOKEN)).toBe(
            "Unlimited",
        );
        expect(amountLine(approveData(MAX_UINT256), USDC)).toBe("Unlimited");
    });

    test("a bundled token keeps its symbol and its scale", () => {
        expect(amountLine(transferData(FIVE_THOUSAND_AT_SIX), USDC)).toBe(
            "5000.0000 USDC",
        );
    });

    test("the amount carried to the status screens is the same string", () => {
        const decoded = decodeCalldata(
            transferData(FIVE_THOUSAND_AT_SIX),
            NOVEL_TOKEN,
        );
        const detail = decoded.details.find((d) => d.label === "Amount");
        expect(detail.rawValue).toBe(
            "5000000000 base units (decimals unknown)",
        );
    });
});