springframeworkguru#18 - Degenerate / Immutable Objects "Side Effects"

(cherry picked from commit 7be4ef5)
patrickcorbett · Apr 22, 2024 · 7faecbc · 7faecbc
1 parent d7890be
commit 7faecbc
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Showing 2 changed files with 6 additions and 4 deletions.
diff --git a/src/main/java/guru/springframework/Dollar.java b/src/main/java/guru/springframework/Dollar.java
@@ -11,7 +11,7 @@ public Dollar(int pAmount) {
         amount = pAmount;
     }
 
-    void times(int pMultiplier) {
-        amount *= pMultiplier;
+    Dollar times(int pMultiplier) {
+        return new Dollar(amount * pMultiplier);
     }
 }
diff --git a/src/test/java/guru/springframework/MoneyTest.java b/src/test/java/guru/springframework/MoneyTest.java
@@ -11,8 +11,10 @@ class MoneyTest {
     @Test
     void testMultiplication() {
         Dollar five = new Dollar(5);
-        five.times(2);
-        Assertions.assertEquals(10, five.amount);
+        Dollar product = five.times(2);
+        Assertions.assertEquals(10, product.amount);
+        product = five.times(3);
+        Assertions.assertEquals(15, product.amount);
     }
 
 }