Question

You must change file HelloWorld.java in hello-java so that the tests all pass

HelloWorld.java

package hw;

public class HelloWorld {

  public String getMessage() {
    return "hello world";
  }

  public int getYear() {
    return 2019;
  }
}

Main.java

package hw;

import java.util.Arrays;

public class Main {

  public static void main(final String[] args) {
    System.out.println("args = " + Arrays.asList(args));
    final HelloWorld instance = new HelloWorld();
    System.out.println(instance.getMessage());
    System.out.println(instance.getYear());
    System.out.println("bye for now");
  }
}

TestHelloWorld.java

package hw;

import static org.junit.Assert.*;

import org.junit.After;
import org.junit.Before;
import org.junit.Test;

public class TestHelloWorld {

  private HelloWorld fixture;

  @Before
  public void setUp() throws Exception {
    fixture = new HelloWorld();
  }

  @After
  public void tearDown() throws Exception {
    fixture = null;
  }

  @Test
  public void getMessage() {
    assertNotNull(fixture);
    assertEquals("hello world", fixture.getMessage());
  }

  @Test
  public void getMessage2() { // this test is broken - fix it!
    assertNull(fixture);
    assertEquals("hello world", fixture.getMessage());
  }

  @Test
  public void getYear() { // this test is OK, fix HelloWorld.java to make it pass!
    assertNotNull(fixture);
    assertEquals(2019, fixture.getYear());
  }
}

Answer 1

package hw;

import static org.junit.Assert.*;

import org.junit.After;
import org.junit.Before;
import org.junit.Test;

public class TestHelloWorld {

    private HelloWorld fixture;

    @Before
    public void setUp() throws Exception {
        fixture = new HelloWorld();
    }

    @After
    public void tearDown() throws Exception {
        fixture = null;
    }

    @Test
    public void getMessage() {
        assertNotNull(fixture);
        assertEquals("hello world", fixture.getMessage());
    }

    @Test
    public void getMessage2() { // this test is broken - fix it!
        /*
        This test is broken because fixture is not null here
        because fixture is assigned an object of HelloWorld in setUp method
        This can not possibly be fixed by changing HelloWorld class in any way
        only way to fix is to by using assertNotNull instead of assertNull here
         */
        assertNotNull(fixture);
        assertEquals("hello world", fixture.getMessage());
    }

    @Test
    public void getYear() { // this test is OK, fix HelloWorld.java to make it pass!
        assertNotNull(fixture);
        assertEquals(2019, fixture.getYear());
    }
}