fix: allow adding negative expenses to expense reports

src/pages/AddExistingExpense.tsx

@@ -52,6 +52,7 @@ import type {OnyxCollection, OnyxEntry} from 'react-native-onyx';
 import React, {useCallback, useEffect, useMemo, useRef, useState} from 'react';
 import {View} from 'react-native';
 
+import canAddTransactionAmountToReport from './canAddTransactionAmountToReport';
 import UnreportedExpenseListItem from './UnreportedExpenseListItem';
 
 type AddExistingExpensePageType = PlatformStackScreenProps<AddExistingExpensesParamList, typeof SCREENS.ADD_EXISTING_EXPENSES_ROOT>;
@@ -121,13 +122,7 @@ function AddExistingExpense({route}: AddExistingExpensePageType) {
 
                 const transactionAmount = getTransactionDetails(item)?.amount ?? 0;
 
-                // Only block negative amounts for unreported expenses.
-                if (transactionAmount < 0 && isUnreported) {
-                    return false;
-                }
-
-                // Zero amount expenses are not allowed in IOU reports
-                if (isIOU && transactionAmount === 0) {
+                if (!canAddTransactionAmountToReport(transactionAmount, isIOU)) {
                     return false;
                 }
 

src/pages/canAddTransactionAmountToReport.ts

@@ -0,0 +1,5 @@
+function canAddTransactionAmountToReport(transactionAmount: number, isIOU: boolean): boolean {
+    return !isIOU || transactionAmount > 0;
+}
+
+export default canAddTransactionAmountToReport;

tests/unit/AddExistingExpenseTest.ts

@@ -1,5 +1,8 @@
+import {getTransactionDetails} from '@libs/ReportUtils';
 import {createUnreportedExpenses} from '@libs/TransactionUtils';
 
+import canAddTransactionAmountToReport from '@pages/canAddTransactionAmountToReport';
+
 import CONST from '@src/CONST';
 import type Transaction from '@src/types/onyx/Transaction';
 
@@ -25,6 +28,23 @@ function generateTransaction(values: Partial<Transaction> = {}): Transaction {
 }
 
 describe('AddExistingExpense', () => {
+    describe('canAddTransactionAmountToReport', () => {
+        const getUnreportedTransactionAmount = (storedAmount: number) => getTransactionDetails(generateTransaction({amount: storedAmount}))?.amount ?? 0;
+
+        test.each([
+            {amountType: 'negative', storedAmount: 1000, isIOU: false, expected: true},
+            {amountType: 'zero', storedAmount: 0, isIOU: false, expected: true},
+            {amountType: 'positive', storedAmount: -1000, isIOU: false, expected: true},
+            {amountType: 'negative', storedAmount: 1000, isIOU: true, expected: false},
+            {amountType: 'zero', storedAmount: 0, isIOU: true, expected: false},
+            {amountType: 'positive', storedAmount: -1000, isIOU: true, expected: true},
+        ])('should handle a $amountType unreported expense with isIOU=$isIOU', ({storedAmount, isIOU, expected}) => {
+            const transactionAmount = getUnreportedTransactionAmount(storedAmount);
+
+            expect(canAddTransactionAmountToReport(transactionAmount, isIOU)).toBe(expected);
+        });
+    });
+
     describe('createUnreportedExpenses', () => {
         it('should mark transactions with DELETE pendingAction as disabled', () => {
             const normalTransaction = generateTransaction({