### Question:
BigIntegers { public static Mapper<BigDecimal, BigInteger> fromBigDecimalToBigInteger() { return new Mapper<BigDecimal, BigInteger>() { @Override public BigInteger map(BigDecimal input) { return input.toBigInteger(); } }; }  static Mapper<String, BigInteger> fromStringToBigInteger(); static Mapper<Integer, BigInteger> fromIntegerToBigInteger(); static Mapper<Long, BigInteger> fromLongToBigInteger(); static Mapper<Float, BigInteger> fromFloatToBigInteger(); static Mapper<Double, BigInteger> fromDoubleToBigInteger(); static Mapper<BigDecimal, BigInteger> fromBigDecimalToBigInteger();  }### Answer:
@Test public void returnsMapperFromBigDecimalToBigInteger() { assertThat(fromBigDecimalToBigInteger().map(new BigDecimal("1234.56")), is(new BigInteger("1234"))); }
@Test(expected = NullPointerException.class) public void throwsNullPointerExceptionWhenMapperFromBigDecimalToBigIntegerPassedNull() { fromBigDecimalToBigInteger().map(null); }