@Test
void path_from_a_to_b_should_be_the_line_ab() {

    AirDistanceRouter router = new AirDistanceRouter();
    Coordinates from = Coordinates.valueOf(0, 0);
    Coordinates to = Coordinates.valueOf(3, 4);
    assertThat(router.getPath(from, to)).containsExactly(from, to);
}