### Question:
Refresher extends AbstractComponent implements NonUIComponent { public void setInterval(int interval) { assert interval > 0 : "interval must be a positive number"; this.interval = interval; } Refresher(); int getInterval(); void setInterval(int interval); HandlerRegistration addListener(final RefreshListener listener); @Override void paintContent(PaintTarget target); @Override void changeVariables(Object source, Map<String, Object> variables);  }### Answer:
@Test(expected = AssertionError.class) public void test_assertsIntervalIsAPositiveNumber() { refresher.setInterval(-10); }