### Question:
BigDecimals { public static Mapper<Long, BigDecimal> fromLongToBigDecimal() { return new Mapper<Long, BigDecimal>() { @Override public BigDecimal map(Long input) { return new BigDecimal(input); } }; } private  BigDecimals(); static Mapper<String, BigDecimal> fromStringToBigDecimal(); static Mapper<Integer, BigDecimal> fromIntegerToBigDecimal(); static Mapper<Long, BigDecimal> fromLongToBigDecimal(); static Mapper<BigInteger, BigDecimal> fromBigIntegerToBigDecimal(); static Mapper<Double, BigDecimal> fromDoubleToBigDecimal(); static Mapper<BigDecimal, String> toPlainString(); static Mapper<BigDecimal, BigDecimal> toScaled(final Integer scale, final RoundingMode roundingMode); static BigDecimal bigDecimal(Integer value); static BigDecimal bigDecimal(Long value); static BigDecimal bigDecimal(Double value); static BigDecimal bigDecimal(String value);  }### Answer:
@Test public void returnsMapperFromLongToBigDecimal() { assertThat(fromLongToBigDecimal().map(123L), is(new BigDecimal("123"))); }
@Test(expected = NullPointerException.class) public void throwsNullPointerExceptionWhenMapperFromLongToBigDecimalPassedNull() { fromLongToBigDecimal().map(null); }