package ru.kirgizovden;

import org.junit.Test;
import static org.hamcrest.core.Is.is;
import static org.junit.Assert.*;

public class CalculateTest { 
        
           @Test
            public void whenSetStopInEchoThenReturnThreeStops() { 
                   Calculate calc  = new Calculate();
                   String result = calc.echo("stop");
                  assertThat(result, is("stop stop stop"));
            }   
      @Test
            public void whenSetNullInEchoThenReturnTwoSpaces() { 
                   Calculate calc  = new Calculate();
                   String result = calc.echo(null);
                  assertThat(result, is("null null null"));
}
  }

add test.java