From 95ff9507b2de8c7f05670fe604cece626a45b3d9 Mon Sep 17 00:00:00 2001
From: Chris <151883835+VeronicDev@users.noreply.github.com>
Date: Thu, 22 Oct 2026 12:51:02 +0100
Subject: [PATCH] Fix: [test] Cover amount parser negative and rounding cases

---
 frontend/src/utils/amount.test.ts | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/frontend/src/utils/amount.test.ts b/frontend/src/utils/amount.test.ts
index a7b0165f..0b2d1efc 100644
--- a/frontend/src/utils/amount.test.ts
+++ b/frontend/src/utils/amount.test.ts
@@ -6,6 +6,32 @@ import {
   hasValidPrecision,
 } from "./amount";
 
+describe("parseAmount edge cases (negative, excessive precision, rounding)", () => {
+  it("handles negative amounts correctly", () => {
+    // parseAmount treats negative values as invalid/zero (returns 0n)
+    expect(parseAmount("-1.5", 7)).toBe(0n);
+    expect(parseAmount("-0", 7)).toBe(0n);
+  });
+
+  it("handles excessive precision by truncating extra decimal places", () => {
+    // 7 decimals max, input has 9
+    expect(parseAmount("1.123456789", 7)).toBe(11234567n);
+    expect(parseAmount("0.000000123", 7)).toBe(1n);
+  });
+
+  it("handles halfway rounding / boundary inputs correctly", () => {
+    // parseAmount currently floors/truncates excess precision rather than rounding
+    expect(parseAmount("1.12345674", 7)).toBe(11234567n);
+    expect(parseAmount("1.12345676", 7)).toBe(11234567n);
+  });
+
+  it("round-trips positive boundary values properly", () => {
+    const val = 1234567n;
+    const formatted = formatAmount(val, 7);
+    expect(parseAmount(formatted, 7)).toBe(val);
+  });
+});
+
 describe("amount parser locale, exponent, whitespace, and empty strings", () => {
   describe("parseAmount with locale and edge inputs", () => {
     it("handles empty and whitespace-only strings", () => {