### Question:
Model implements QueryResult { public boolean isValid() { return true; }  boolean isValid(); final boolean exists(); final boolean save(); final boolean save(Transaction t); final void saveAsync(); final void saveAsync(final OnSavedCallback callback); final void delete(); final void delete(Transaction t); final void deleteAsync(); final void deleteAsync(final OnDeletedCallback callback);  }### Answer:
@Test public void isValid() { TestModel m = new TestModel(); m.title = "hej"; m.valid = false; assertFalse(m.save()); m.valid = true; assertTrue(m.save()); }