@Test
public void buildsReflection() {

    final Polyline<Double> input = new PtsPolyline<>(
        Arrays.asList(
            new RandomPoint<>(), new RandomPoint<>(),
            new RandomPoint<>(), new RandomPoint<>()
        )
    );
    final RandomPoint<Double> across = new RandomPoint<>();
    final Polyline<Double> result = new PtReflectionPolyLine<>(across, input);
    for (int idx = 0; idx < result.points().size(); ++idx) {
        PtReflectionPolyLineTest.equal(
            result.points().get(idx),
            PtReflectionPolyLineTest.reflected(
                across, input.points().get(idx)
            )
        );
    }
}