Test: check prime for non-prime numbers

src/test/java/CalculationsTest.java

@@ -1,7 +1,7 @@
 import org.junit.Test;
-
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
+import static org.junit.Assert.assertFalse;
 
 public class CalculationsTest {
 
@@ -46,9 +46,16 @@ public class CalculationsTest {
 
     @Test
     public void testIsPrime() {
-        assertTrue(Calculations.isPrime(2)); // Prime number
-        assertTrue(Calculations.isPrime(3)); // Prime number
-        assertTrue(Calculations.isPrime(5)); // Prime number
+        // Prime
+        assertTrue(Calculations.isPrime(2));
+        assertTrue(Calculations.isPrime(3));
+        assertTrue(Calculations.isPrime(5));
+
+        // Non-Prime
+        assertFalse(Calculations.isPrime(22));
+        assertFalse(Calculations.isPrime(25));
+        assertFalse(Calculations.isPrime(27));
+        assertFalse(Calculations.isPrime(30));
     }
 }