@Test
public void onFileChangeEvent() {

    when(fileMock.getValue()).thenReturn(VALUE);
    ChangeEvent changeEventMock = mock(ChangeEvent.class);
    ((FileUploadPopupView) popupView).onFileChangeEvent(changeEventMock);
    verify(fileMock, times(1)).getValue();
    verify(fileTextMock, times(1)).setValue(eq(VALUE));
}