[long-to-bigdecimal] Convert Long to BigDecimal in Java (#14372)

* [long-to-bigdecimal] Convert Long to BigDecimal in Java

* [long-to-bigdecimal] renaming var

core-java-modules/core-java-numbers-conversions/src/test/java/com/baeldung/longtobigdecimal/LongToBigDecimalUnitTest.java

@@ -0,0 +1,70 @@
+package com.baeldung.longtobigdecimal;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotSame;
+import static org.junit.jupiter.api.Assertions.assertSame;
+
+import java.math.BigDecimal;
+
+import org.junit.jupiter.api.Test;
+
+public class LongToBigDecimalUnitTest {
+    @Test
+    void whenUsingTheConstructor_thenGetTheExpectedBigDecimal() {
+        Long num4 = 4L;
+        BigDecimal result4 = new BigDecimal(num4);
+        assertEquals(new BigDecimal("4"), result4);
+
+        Long num42 = -42L;
+        BigDecimal result42 = new BigDecimal(num42);
+        assertEquals(new BigDecimal("-42"), result42);
+    }
+
+    @Test
+    void whenUsingTheValueOf_thenGetTheExpectedBigDecimal() {
+        Long num4 = 4L;
+        BigDecimal result4 = BigDecimal.valueOf(num4);
+        assertEquals(new BigDecimal("4"), result4);
+
+        Long num42 = -42L;
+        BigDecimal result42 = BigDecimal.valueOf(num42);
+        assertEquals(new BigDecimal("-42"), result42);
+    }
+
+    @Test
+    void when0To10AndUsingTheValueOfMethod_thenGetTheSameBigDecimalObject() {
+        Long num4 = 4L;
+        BigDecimal bd4_1 = BigDecimal.valueOf(num4);
+        BigDecimal bd4_2 = BigDecimal.valueOf(num4);
+        BigDecimal bd4_3 = BigDecimal.valueOf(num4);
+        assertSame(bd4_1, bd4_2);
+        assertSame(bd4_2, bd4_3);
+
+        Long num42 = -42L;
+        BigDecimal bd42_1 = BigDecimal.valueOf(num42);
+        BigDecimal bd42_2 = BigDecimal.valueOf(num42);
+        BigDecimal bd42_3 = BigDecimal.valueOf(num42);
+        assertNotSame(bd42_1, bd42_2);
+        assertNotSame(bd42_1, bd42_3);
+        assertNotSame(bd42_2, bd42_3);
+    }
+
+    @Test
+    void when0To10AndUsingTheConstructor_thenGetTheDifferentBigDecimalObjects() {
+        Long num4 = 4L;
+        BigDecimal result1 = new BigDecimal(num4);
+        BigDecimal result2 = new BigDecimal(num4);
+        BigDecimal result3 = new BigDecimal(num4);
+        assertNotSame(result1, result2);
+        assertNotSame(result2, result3);
+        assertNotSame(result1, result3);
+
+        Long num42 = -42L;
+        BigDecimal bd42_1 = new BigDecimal(num42);
+        BigDecimal bd42_2 = new BigDecimal(num42);
+        BigDecimal bd42_3 = new BigDecimal(num42);
+        assertNotSame(bd42_1, bd42_2);
+        assertNotSame(bd42_1, bd42_3);
+        assertNotSame(bd42_2, bd42_3);
+    }
+}