### Question:
BigDecimals { public static Mapper<String, BigDecimal> fromStringToBigDecimal() { return new Mapper<String, BigDecimal>() { @Override public BigDecimal map(String 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 returnsMapperFromStringToBigDecimal() { assertThat(fromStringToBigDecimal().map("123.45"), is(new BigDecimal("123.45"))); }
@Test(expected = NullPointerException.class) public void throwsNullPointerExceptionWhenMapperFromStringToBigDecimalPassedNull() { fromStringToBigDecimal().map(null); }