private static final class RoundToDoubleTester {
    private final BigInteger input;
    private final Map<RoundingMode, Double> expectedValues = new EnumMap<>(RoundingMode.class);
    private boolean unnecessaryShouldThrow = false;

    RoundToDoubleTester(BigInteger input) {
      this.input = input;
    }

    @CanIgnoreReturnValue