Add MaxValueTest and remove main from MaxValue (#4756)

* Create MaxValueTest.java

* Update MaxValue.java

src/main/java/com/thealgorithms/maths/MaxValue.java

@@ -1,24 +1,8 @@
 package com.thealgorithms.maths;
 
-import java.util.Random;
-
-public class MaxValue {
-
-    /**
-     * Driver Code
-     */
-    public static void main(String[] args) {
-        Random rand = new Random();
-
-        /* test 100 times using rand numbers */
-        for (int i = 1; i <= 100; ++i) {
-            /* generate number from -50 to 49 */
-            int a = rand.nextInt(100) - 50;
-            int b = rand.nextInt(100) - 50;
-            assert max(a, b) == Math.max(a, b);
-        }
+public final class MaxValue {
+    private MaxValue() {
     }
-
     /**
      * Returns the greater of two {@code int} values. That is, the result is the
      * argument closer to the value of {@link Integer#MAX_VALUE}. If the

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

@@ -0,0 +1,14 @@
+package com.thealgorithms.maths;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+public class MaxValueTest {
+    @Test
+    public void maxTest() {
+        assertEquals(-1, MaxValue.max(-1, -3));
+        assertEquals(3, MaxValue.max(3, 2));
+        assertEquals(5, MaxValue.max(5, 5));
+    }
+}