def METHOD_NAME(self):
    self.state.selected_conversation = 1
    self.state.add_file(1, "some_file_id")
    self.state.add_file(1, "another_file_id")
    self.state.add_file("conversation that's not selected", "unrelated_file")
    self.state.file("unrelated_file").is_downloaded = False  # to be explicit
    self.state.file("some_file_id").is_downloaded = True
    self.state.file("another_file_id").is_downloaded = True
    assert not self.state.selected_conversation_has_downloadable_files
    self.state.file("some_file_id").is_downloaded = False
    assert self.state.selected_conversation_has_downloadable_files