Build Gradle base java junit code

FizBuzz.txt

Given a number, the program should: 
Return "Fizz" if the number is a multiple of 3; 
Return "Buzz" if the number is a multiple of 5; 
Return "FizzBuzz" if the number is a multiple of both.
Return the same number if the number is not a multiple of one of them or both; 

FizzBuzzTest.java

import fizzbuzz.FizzBuzz;
import org.junit.Test;

import static org.hamcrest.core.Is.is;
import static org.junit.Assert.assertThat;

public class FizzBuzzTest {
   @Test
   public void shouldReturnFizzWhenNumberIsMultipleOf3() {
       int number = 3;
       FizzBuzz fizzBuzz = new FizzBuzz();

       String convertedNumber = fizzBuzz.convert(number);

       assertThat(convertedNumber, is("fizz"));
   }
}