Junit Test Keeps Failing with IllegalArgumentException

Question

I've tried placing try and catch blocks as well as with throw new IllegalArgumentException but none of this stops the failed test. What am I missing here? Thank you.

package com.udacity.jdnd.course1.service;

public class FizzBuzzService {

    /**
     * If number is divisible by 3, return "Fizz". If divisible by 5,
     * return "Buzz", and if divisible by both, return "FizzBuzz". Otherwise,
     * return the number itself.
     *
     * @Throws IllegalArgumentException for values < 1
     */
    public String fizzBuzz(int number) {

        String result = "";
        try {
            if (number % 3 == 0 && number % 5 == 0) {
                result = "FizzBuzz";
            } else {
                if (number % 3 == 0) {
                    result = "Fizz";
                } else if (number % 5 == 0) {
                    result = "Buzz";
                } else {
                    return Integer.toString(number);
                }
            }

            if (number == 0){
                throw new IllegalArgumentException("Value is zero ");
            }

//            return result;
//        }
    } catch(IllegalArgumentException i){
      System.out.println("this what is thrown " + i);
    }

        return result;

    }


}

package com.udacity.jdnd.course1;

import com.udacity.jdnd.course1.service.FizzBuzzService;
import org.junit.jupiter.api.Test;
import org.springframework.boot.test.context.SpringBootTest;

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

@SpringBootTest
class Course1ApplicationTests {

    @Test
    void testFizzBuzz(){
        FizzBuzzService fbs = new FizzBuzzService();

        // check non-divisible numbers return themselves
        assertEquals("1", fbs.fizzBuzz(1));
        assertEquals("47", fbs.fizzBuzz(47));
        assertEquals("121", fbs.fizzBuzz(121));

        // check numbers divisible by 3
        assertEquals("Fizz", fbs.fizzBuzz(3));
        assertEquals("Fizz", fbs.fizzBuzz(333));

        //check numbers divisible by 5
        assertEquals("Buzz", fbs.fizzBuzz(5));
        assertEquals("Buzz", fbs.fizzBuzz(85));

        //check numbers divisible by 3 and 5
        assertEquals("FizzBuzz", fbs.fizzBuzz(15));
        assertEquals("FizzBuzz", fbs.fizzBuzz(75));

        //check invalid inputs
        assertThrows(IllegalArgumentException.class, () -> fbs.fizzBuzz(0));
        assertThrows(IllegalArgumentException.class, () -> fbs.fizzBuzz(-1));
    }
}

The error I get is:

org.opentest4j.AssertionFailedError: Expected java.lang.IllegalArgumentException to be thrown, but nothing was thrown.

at org.junit.jupiter.api.AssertThrows.assertThrows(AssertThrows.java:71)

Answer 1

By placing this at the beginning and getting rid of the try/catch block

if (number == 0 || number == -1){
                throw new IllegalArgumentException("Value is zero ");
            }