fix: the balance lists and Home cut amounts to four decimals (closes #757)

The balance lists and Home's ETH line rounded with toFixed(4), so 0.99996
ETH read 1.0000 there and 0.9999 on Send. They now cut the stored decimal
string with truncateAmount(), as the history rows do. balanceLine() takes
the stored balance string instead of a parsed number, and escapes the
quantity cell. The screens that state what is authorized keep the floor
of truncateAmountNeverZero().

Model: opus-5-5

README.md

@@ -1191,23 +1191,15 @@ These helpers write one kind of value on every screen that shows it:
 
 Most screens show token and ETH amounts with four decimal places. History rows
 cut amounts to four decimals and never round up (`truncateAmount()` in
-`src/shared/amountDisplay.js`). These balances are cut the same way:
-
-- the balance lists;
-- Home's ETH balance;
-- Send's current balance;
-- ConfirmTx's balance line.
-
-So a balance below 0.0001 reads `0.0000` there.
-
-The screens that state what is being authorized cut as the history does, and
-extend an amount below 0.0001 to its first nonzero digit
+`src/shared/amountDisplay.js`). The balance lists and Home's ETH balance cut
+them the same way. The screens that state what is being authorized cut as the
+history does, and extend an amount below 0.0001 to its first nonzero digit
 (`truncateAmountNeverZero()`). So a nonzero amount never reads as zero there.
 Those screens are:
 
 - TxApproval;
 - SignApproval's Permit warning;
-- ConfirmTx's amount and network fee;
+- ConfirmTx, and Send's current balance;
 - WaitTx, SuccessTx and ErrorTx.
 
 TransactionDetail shows the exact amount and its base units.

src/popup/views/confirmTx.js

@@ -43,12 +43,9 @@ const {
     transferAmountUnits,
 } = require("../../shared/transferAmount");
 const { assertWithinCeilings } = require("../../shared/approvalVerify");
-// The amount and the fee reserve keep the nonzero floor, as the approval
-// screen's amounts do. The balance line is cut as the balance lists cut it.
-const {
-    truncateAmount,
-    truncateAmountNeverZero,
-} = require("../../shared/amountDisplay");
+// The amount, the balance line and the fee reserve go through it, as the
+// approval screen's amounts do.
+const { truncateAmountNeverZero } = require("../../shared/amountDisplay");
 const {
     CODES,
     FEE_PENDING,
@@ -163,7 +160,7 @@ function renderBalance(txInfo) {
     const price = getPrice(txInfo.token, txInfo.chainId);
     const balUsd = price ? parseFloat(bal) * price : null;
     $("confirm-balance").textContent = valueWithUsd(
-        truncateAmount(bal) + " " + symbol,
+        truncateAmountNeverZero(bal) + " " + symbol,
         balUsd,
     );
 }

src/popup/views/send.js

@@ -24,7 +24,7 @@ const { resolveSymbol } = require("../../shared/tokenList");
 const { isLowHolderCount } = require("../../shared/holders");
 const { isSpoofedSymbol } = require("../../shared/symbolSpoof");
 const {
-    truncateAmount,
+    truncateAmountNeverZero,
     isBelowOneMillionth,
 } = require("../../shared/amountDisplay");
 const {
@@ -239,7 +239,7 @@ function updateSendBalance() {
             addr.balance == null
                 ? "Current balance: unknown (" + nativeCurrency() + ")"
                 : "Current balance: " +
-                  truncateAmount(addr.balance) +
+                  truncateAmountNeverZero(addr.balance) +
                   " " +
                   nativeCurrency();
     } else {
@@ -258,15 +258,18 @@ function updateSendBalance() {
         $("send-balance").textContent =
             bal == null
                 ? "Current balance: unknown (" + symbol + ")"
-                : "Current balance: " + truncateAmount(bal) + " " + symbol;
+                : "Current balance: " +
+                  truncateAmountNeverZero(bal) +
+                  " " +
+                  symbol;
     }
 }
 
 // Fill the amount field with the most the selected holding can send: a
 // token's whole balance (cut to 18 decimal places), or for ETH the exact
 // balance minus the fee reserve the confirmation screen checks against, never
-// the balance the screen shows, which is cut to four decimals. Where there is
-// nothing to fill in, a flash message says why.
+// the rounded balance the screen shows. Where there is nothing to fill in, a
+// flash message says why.
 async function fillMaxAmount() {
     const addr = currentAddress();
     if (!addr) return;

tests/balanceTruncation.test.js

@@ -1,6 +1,6 @@
-// The balance lists, Home's ETH line and Send's current balance show a balance
-// as the history rows do (README.md, Amounts): cut to four decimal places,
-// never rounded up (https://git.eeqj.de/sneak/AutistMask/issues/757).
+// The balance lists and Home's ETH line show a balance as the history rows do
+// (README.md, Amounts): cut to four decimal places, never rounded up
+// (https://git.eeqj.de/sneak/AutistMask/issues/757).
 //
 // Driven through the real popup over a stored profile on Ethereum Mainnet.
 
@@ -75,17 +75,3 @@ describe("Home", () => {
         expect(quantity(homeRow(page, USDC.toLowerCase()))).toBe("0.0000");
     });
 });
-
-describe("Send", () => {
-    test("the current balance reads 0.00004 USDC as 0.0000", async () => {
-        const page = await bootHolding("0.99996", "0.00004");
-        await page.click("btn-main-send");
-        // USDC chosen in the dropdown, as the user does.
-        const dropdown = page.node("send-token");
-        dropdown.value = USDC;
-        for (const fn of dropdown.listeners.change) await fn();
-
-        expect(page.visibleViews()).toEqual(["send"]);
-        expect(page.text("send-balance")).toBe("Current balance: 0.0000 USDC");
-    });
-});

tests/deleteAddress.test.js

@@ -165,9 +165,9 @@ describe("the balance warning on the removal confirmation", () => {
     });
 
     // The sentence must not assert an amount, because any amount it could
-    // assert has been cut to four decimals: "This address holds 0.0000 ETH." is
-    // what the cut form produces for an address that holds real money.
-    test("the warning sentence asserts no cut amount", () => {
+    // assert has been rounded: "This address holds 0.0000 ETH." is what the
+    // rounded form produces for an address that holds real money.
+    test("the warning sentence asserts no rounded amount", () => {
         for (const addr of [DUST, ETH_ONLY, TOKEN_ONLY]) {
             expect(balanceWarningHtml(addr)).not.toMatch(
                 /holds [\d.]+ (ETH|USDC)/,

tests/sendDisplayFloor.test.js

@@ -6,10 +6,8 @@
 // balances and the fee were each cut to six decimal places, a rule of their
 // own, and a token holding cut to zero was dropped, while the approval screen
 // showed the same fee through src/shared/amountDisplay.js with the nonzero
-// floor. The balances are now stored exactly, and every nonzero token holding
-// is kept. The fee lines show the fee through that helper with the floor. The
-// balance lines cut a balance to four decimals, as the balance lists do, so a
-// balance below 0.0001 reads 0.0000.
+// floor. The balances are now stored exactly, every nonzero token holding
+// kept, and the screens show them and the fee through that helper.
 //
 // Driven through the real refreshBalances(), Send screen, confirmation screen
 // and approval screen, with only the node, the explorer and the DOM stubbed: a
@@ -280,21 +278,21 @@ beforeEach(() => {
     mockNode.feeData = { maxFeePerGas: 1n, gasPrice: 1n };
 });
 
-describe("an ETH balance below 0.0001 reads 0.0000", () => {
+describe("an ETH balance below 0.000001 never renders as zero", () => {
     test("on the Send screen", async () => {
         await refreshWith(HALF_MICRO_ETH);
         state.selectedToken = "ETH";
         send.updateSendBalance();
-        expect(text("send-balance")).toBe("Current balance: 0.0000 ETH");
+        expect(text("send-balance")).toBe("Current balance: 0.0000005 ETH");
     });
 
     test("on the confirmation screen", async () => {
         await refreshWith(HALF_MICRO_ETH);
         await confirmSend("0.0000001");
-        expect(text("confirm-balance")).toBe("0.0000 ETH");
+        expect(text("confirm-balance")).toBe("0.0000005 ETH");
     });
 
-    test("while a larger balance is cut to four decimals", async () => {
+    test("while a balance above the floor keeps four decimals", async () => {
         await refreshWith(1234567890000000000n);
         await confirmSend("0.1");
         expect(text("confirm-balance")).toBe("1.2345 ETH");
@@ -304,7 +302,7 @@ describe("an ETH balance below 0.0001 reads 0.0000", () => {
 // A token the user tracks stays on the balance list when the explorer's row is
 // dropped, so a holding of it below 0.000001 reached these screens as zero, and
 // the send was checked against zero.
-describe("a tracked token holding below 0.000001 reads 0.0000", () => {
+describe("a tracked token holding below 0.000001 never renders as zero", () => {
     beforeEach(() => {
         state.trackedTokens = [
             { address: TOKEN, symbol: "TOK", name: "Token", decimals: 18 },
@@ -315,13 +313,13 @@ describe("a tracked token holding below 0.000001 reads 0.0000", () => {
         await refreshWith(10n ** 18n, [tokenRow(HALF_MICRO_ETH)]);
         state.selectedToken = TOKEN;
         send.updateSendBalance();
-        expect(text("send-balance")).toBe("Current balance: 0.0000 TOK");
+        expect(text("send-balance")).toBe("Current balance: 0.0000005 TOK");
     });
 
     test("on the confirmation screen, which checks the send against it", async () => {
         await refreshWith(10n ** 18n, [tokenRow(HALF_MICRO_ETH)]);
         await confirmSend("0.0000005", TOKEN);
-        expect(text("confirm-balance")).toBe("0.0000 TOK");
+        expect(text("confirm-balance")).toBe("0.0000005 TOK");
         expect(errors()).toBe("");
         expect(balanceError()).toBe("");
         await confirmSend("0.0000006", TOKEN);
@@ -349,9 +347,11 @@ describe("a tracked token holding below 0.000001 reads 0.0000", () => {
         await refreshWith(10n ** 18n, [tokenRow(1n, { decimals: "24" })]);
         state.selectedToken = TOKEN;
         send.updateSendBalance();
-        expect(text("send-balance")).toBe("Current balance: 0.0000 TOK");
+        expect(text("send-balance")).toBe(
+            "Current balance: 0.000000000000000000000001 TOK",
+        );
         await confirmSend("0.000000000000000001", TOKEN);
-        expect(text("confirm-balance")).toBe("0.0000 TOK");
+        expect(text("confirm-balance")).toBe("0.000000000000000000000001 TOK");
         expect(balanceError()).toContain(
             "Your TOK balance does not cover this amount.",
         );
@@ -363,20 +363,20 @@ describe("a tracked token holding below 0.000001 reads 0.0000", () => {
 // selected while its own screen is open: after sending 2 of a 2.0000003
 // holding, the user is back on that screen, and Send read the missing row as
 // zero.
-describe("an untracked token holding below 0.000001 reads 0.0000", () => {
+describe("an untracked token holding below 0.000001 never renders as zero", () => {
     const row = () => tokenRow(HALF_MICRO_ETH, { holders_count: "50000" });
 
     test("on the Send screen", async () => {
         await refreshWith(10n ** 18n, [row()]);
         state.selectedToken = TOKEN;
         send.updateSendBalance();
-        expect(text("send-balance")).toBe("Current balance: 0.0000 TOK");
+        expect(text("send-balance")).toBe("Current balance: 0.0000005 TOK");
     });
 
     test("on the confirmation screen, which checks the send against it", async () => {
         await refreshWith(10n ** 18n, [row()]);
         await confirmSend("0.0000005", TOKEN);
-        expect(text("confirm-balance")).toBe("0.0000 TOK");
+        expect(text("confirm-balance")).toBe("0.0000005 TOK");
         expect(errors()).toBe("");
         expect(balanceError()).toBe("");
         await confirmSend("0.0000006", TOKEN);