Add testcase to Ceil Algorithm (#3183)

Co-authored-by: Yang Libin <contact@yanglibin.info>

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

@@ -4,14 +4,6 @@ import java.util.Random;
 
 public class Ceil {
 
-    public static void main(String[] args) {
-        Random random = new Random();
-        for (int i = 1; i <= 1000; ++i) {
-            double randomNumber = random.nextDouble();
-            assert ceil(randomNumber) == Math.ceil(randomNumber);
-        }
-    }
-
     /**
      * Returns the smallest (closest to negative infinity)
      *

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

@@ -0,0 +1,17 @@
+package com.thealgorithms.maths;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+public class CeilTest {
+
+    @Test
+    void testCeil() {
+        assertEquals(8, Ceil.ceil(7.057));
+        assertEquals(8, Ceil.ceil(7.004));
+        assertEquals(-13, Ceil.ceil(-13.004));
+        assertEquals(1, Ceil.ceil(.98));
+        assertEquals(-11, Ceil.ceil(-11.357));
+    }
+}