@Test
public void testUserChange() {
when(view.getUser()).thenReturn(USER);
// emulates the presenter method executed from the UI.
mainPanel.onUserChange();
verify(view, times(1)).getUser();
// the handler should have been invoked and collected the expected value.
assertEquals(USER, user);
}
@Test
public void testGetUser() {
when(view.getUser()).thenReturn(USER);
assertEquals(USER, mainPanel.getUser());
}