Code refactor for AbsoluteMax improvements (#3020)

Fix #3019

Co-authored-by: Yang Libin <szuyanglb@outlook.com>

src/test/java/com/thealgorithms/maths/AbsoluteMaxTest.java

@@ -0,0 +1,21 @@
+package com.thealgorithms.maths;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+public class AbsoluteMaxTest {
+
+    @Test
+    void testGetMaxValue() {
+        assertEquals(16, AbsoluteMax.getMaxValue(-2, 0, 16));
+        assertEquals(-10, AbsoluteMax.getMaxValue(3, -10, -2));
+    }
+
+    @Test
+    void testGetMaxValueWithNoArguments() {
+        Exception exception = assertThrows(IllegalArgumentException.class, () -> AbsoluteMax.getMaxValue());
+        assertEquals("Numbers array cannot be empty", exception.getMessage());
+    }
+}