### Question:
Question1 { public static int addUp(Stream<Integer> numbers) { return Exercises.replaceThisWithSolution(); }  static int addUp(Stream<Integer> numbers); static List<String> getNamesAndOrigins(List<Artist> artists); static List<Album> getAlbumsWithAtMostThreeTracks(List<Album> input);  }### Answer:
@Test public void addsEmptyList() { int result = Question1.addUp(Stream.empty()); assertEquals(0, result); }
@Test public void addsListWithValues() { int result = Question1.addUp(Stream.of(1, 3, -2)); assertEquals(2, result); }