BAEL-821 - Added unit test for different round methods.

core-java/src/test/java/com/baeldung/maths/RoundTest.java

@@ -0,0 +1,29 @@
+package com.baeldung.maths;
+
+import org.apache.commons.math3.util.Precision;
+import org.decimal4j.util.DoubleRounder;
+import org.junit.Assert;
+import org.junit.Test;
+
+public class RoundTest {
+    private double value = 2.03456d;
+    private int places = 2;
+    private double delta = 0.0d;
+    private double expected = 2.03d;
+
+    @Test
+    public void givenDecimalNumber_roundToNDecimalPlaces_getExpectedResult() {   
+        Assert.assertEquals(expected, Round.round(value, places), delta);
+        Assert.assertEquals(expected, Round.roundOptional(value, places), delta);
+        Assert.assertEquals(expected, Precision.round(value, places), delta);
+        Assert.assertEquals(expected, DoubleRounder.round(value, places), delta);
+        
+        places = 3;
+        expected = 2.035d;
+        
+        Assert.assertEquals(expected, Round.round(value, places), delta);
+        Assert.assertEquals(expected, Round.roundOptional(value, places), delta);
+        Assert.assertEquals(expected, Precision.round(value, places), delta);
+        Assert.assertEquals(expected, DoubleRounder.round(value, places), delta);
+    }
+}