Unit Tests

package org.exersises.example.test;

public class Circle {
	
    public static double calculateArea(double radius) {
        return Math.PI * radius * radius;
    }

}

package org.exersises.example.test;

import static org.junit.jupiter.api.Assertions.*;

import org.junit.jupiter.api.Test;
import org.junit.Assert;

class CircleTest {

	@Test
	void test() {
		fail("Not yet implemented");
	}
	
	@Test 
	public void givenRadius_whenCalculateArea_thenReturnArea() {
	    double actualArea = Circle.calculateArea(1d);
	    double expectedArea = 3.141592653589793;
	    Assert.assertEquals(expectedArea, actualArea); 
	}	

}

class Solution {
  public static void main(String[] args) {
    ArrayList<String> strings = new ArrayList<String>();
    strings.add("Hello, World!");
    strings.add("Welcome to CoderPad.");
    strings.add("This pad is running Java " + Runtime.version().feature());

    for (String string : strings) {
      System.out.println(string);
    }

    SolutionTest test = new SolutionTest();
    test.givenTen_whenFactorial_thenReturnNumber();
    //var res = Solution.factorial(10);
    //System.out.println(res);

  }

  public static int factorial(int n) {
    if (n<0) return -1; 
    if (n == 1 || n == 0) return n;
    return n*factorial(n-1);    
  }

}

class SolutionTest {

  @Test
  public void givenTen_whenFactorial_thenReturnNumber() {
    int actualFactorial = Solution.factorial(10);
    int expectedFactorial = 36288001;

    Assert.assertEquals(expectedFactorial, actualFactorial);


  }

}