FINERACT-2181: Add null safety to Money class

fineract-core/src/main/java/org/apache/fineract/organisation/monetary/domain/Money.java

@@ -224,6 +224,9 @@ public class Money implements Comparable<Money> {
     public Money plus(final Iterable<? extends Money> moniesToAdd) {
         BigDecimal total = this.amount;
         for (final Money moneyProvider : moniesToAdd) {
+            if (moneyProvider == null) {
+                continue;
+            }
             final Money money = checkCurrencyEqual(moneyProvider);
             total = total.add(money.amount);
         }
@@ -235,6 +238,10 @@ public class Money implements Comparable<Money> {
     }
 
     public Money plus(final Money moneyToAdd, final MathContext mc) {
+        if (moneyToAdd == null) {
+            return this;
+        }
+
         final Money toAdd = checkCurrencyEqual(moneyToAdd);
         return this.plus(toAdd.getAmount(), mc);
     }
@@ -264,6 +271,9 @@ public class Money implements Comparable<Money> {
     }
 
     public Money minus(final Money moneyToSubtract, final MathContext mc) {
+        if (moneyToSubtract == null) {
+            return this;
+        }
         final Money toSubtract = checkCurrencyEqual(moneyToSubtract);
         return this.minus(toSubtract.getAmount(), mc);
     }
@@ -273,6 +283,9 @@ public class Money implements Comparable<Money> {
     }
 
     public Money add(final Money moneyToAdd, final MathContext mc) {
+        if (moneyToAdd == null) {
+            return this;
+        }
         final Money toAdd = checkCurrencyEqual(moneyToAdd);
         return this.add(toAdd.getAmount(), mc);
     }

fineract-core/src/test/java/org/apache/fineract/organisation/monetary/domain/MoneyTest.java

@@ -0,0 +1,112 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.fineract.organisation.monetary.domain;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.math.BigDecimal;
+import java.math.MathContext;
+import java.math.RoundingMode;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+import org.junit.jupiter.api.AfterAll;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.MockedStatic;
+import org.mockito.Mockito;
+import org.mockito.junit.jupiter.MockitoExtension;
+import org.mockito.junit.jupiter.MockitoSettings;
+import org.mockito.quality.Strictness;
+
+@ExtendWith(MockitoExtension.class)
+@MockitoSettings(strictness = Strictness.LENIENT)
+class MoneyTest {
+
+    private static MockedStatic<MoneyHelper> moneyHelper = Mockito.mockStatic(MoneyHelper.class);
+    private static final MonetaryCurrency CURRENCY = new MonetaryCurrency("USD", 2, null);
+    private static final MathContext MATH_CONTEXT = MathContext.DECIMAL64;
+
+    private static Money tenDollars;
+    private static Money oneDollar;
+
+    @BeforeAll
+    static void setUp() {
+        moneyHelper.when(MoneyHelper::getMathContext).thenReturn(new MathContext(12, RoundingMode.UP));
+        moneyHelper.when(MoneyHelper::getRoundingMode).thenReturn(RoundingMode.UP);
+        tenDollars = Money.of(CURRENCY, BigDecimal.TEN);
+        oneDollar = Money.of(CURRENCY, BigDecimal.ONE);
+    }
+
+    @AfterAll
+    static void tearDown() {
+        moneyHelper.close();
+    }
+
+    @Test
+    void testPlusWithNullInIterable() {
+        List<Money> monies = Arrays.asList(oneDollar, null, oneDollar);
+        Money result = tenDollars.plus(monies);
+        assertEquals(0, result.getAmount().compareTo(new BigDecimal("12.00")), "Should sum non-null values and skip nulls");
+    }
+
+    @Test
+    void testPlusWithEmptyIterable() {
+        List<Money> emptyList = Collections.emptyList();
+        Money result = tenDollars.plus(emptyList);
+        assertEquals(0, result.getAmount().compareTo(BigDecimal.TEN), "Should return the same amount when adding empty list");
+    }
+
+    @Test
+    void testPlusWithNullMoney() {
+        Money result = tenDollars.plus((Money) null, MATH_CONTEXT);
+        assertEquals(0, result.getAmount().compareTo(BigDecimal.TEN), "Should return the same amount when adding null Money");
+    }
+
+    @Test
+    void testMinusWithNullMoney() {
+        Money result = tenDollars.minus((Money) null, MATH_CONTEXT);
+        assertEquals(0, result.getAmount().compareTo(BigDecimal.TEN), "Should return the same amount when subtracting null Money");
+    }
+
+    @Test
+    void testAddWithNullMoney() {
+        Money result = tenDollars.add((Money) null, MATH_CONTEXT);
+        assertEquals(0, result.getAmount().compareTo(BigDecimal.TEN), "Should return the same amount when adding null Money");
+    }
+
+    @Test
+    void testPlusMoney() {
+        Money result = tenDollars.plus(oneDollar, MATH_CONTEXT);
+        assertEquals(0, result.getAmount().compareTo(new BigDecimal("11.00")), "Should correctly add two Money amounts");
+    }
+
+    @Test
+    void testMinusMoney() {
+        Money result = tenDollars.minus(oneDollar, MATH_CONTEXT);
+        assertEquals(0, result.getAmount().compareTo(new BigDecimal("9.00")), "Should correctly subtract two Money amounts");
+    }
+
+    @Test
+    void testAddMoney() {
+        Money result = tenDollars.add(oneDollar, MATH_CONTEXT);
+        assertEquals(0, result.getAmount().compareTo(new BigDecimal("11.00")), "Should correctly add two Money amounts");
+    }
+}