Looking for unit testing data for Block.Bits to & from a JSON-RPC string I'm trying to convert the JSON-RPC result of a Block's compressed bits property into a C# float with the following constraint

 //3  bytes mantissa, the leading byte as exponent (where only the 5 lowest bits are used) and its base is 256


Is there any sample data I can use to verify my implementation is working?  

A JSON-RPC string, and it's corresponding 256-bit output in Big Endian format would be a great help.
You're looking for bignum_tests.cpp:

BOOST_AUTO_TEST_CASE(bignum_SetCompact)
{
    CBigNum num;
    num.SetCompact(0);
    BOOST_CHECK_EQUAL(num.GetHex(), "0");
    BOOST_CHECK_EQUAL(num.GetCompact(), 0);

    num.SetCompact(0x00123456);
    BOOST_CHECK_EQUAL(num.GetHex(), "0");
    BOOST_CHECK_EQUAL(num.GetCompact(), 0);

    num.SetCompact(0x01123456);
    BOOST_CHECK_EQUAL(num.GetHex(), "12");
    BOOST_CHECK_EQUAL(num.GetCompact(), 0x01120000);

    // Make sure that we don't generate compacts with the 0x00800000 bit set
    num = 0x80;
    BOOST_CHECK_EQUAL(num.GetCompact(), 0x02008000);

    num.SetCompact(0x01fedcba);
    BOOST_CHECK_EQUAL(num.GetHex(), "-7e");
    BOOST_CHECK_EQUAL(num.GetCompact(), 0x01fe0000);

    num.SetCompact(0x02123456);
    BOOST_CHECK_EQUAL(num.GetHex(), "1234");
    BOOST_CHECK_EQUAL(num.GetCompact(), 0x02123400);

    num.SetCompact(0x03123456);
    BOOST_CHECK_EQUAL(num.GetHex(), "123456");
    BOOST_CHECK_EQUAL(num.GetCompact(), 0x03123456);

    num.SetCompact(0x04123456);
    BOOST_CHECK_EQUAL(num.GetHex(), "12345600");
    BOOST_CHECK_EQUAL(num.GetCompact(), 0x04123456);

    num.SetCompact(0x04923456);
    BOOST_CHECK_EQUAL(num.GetHex(), "-12345600");
    BOOST_CHECK_EQUAL(num.GetCompact(), 0x04923456);

    num.SetCompact(0x05009234);
    BOOST_CHECK_EQUAL(num.GetHex(), "92340000");
    BOOST_CHECK_EQUAL(num.GetCompact(), 0x05009234);

    num.SetCompact(0x20123456);
    BOOST_CHECK_EQUAL(num.GetHex(), "1234560000000000000000000000000000000000000000000000000000000000");
    BOOST_CHECK_EQUAL(num.GetCompact(), 0x20123456);

    num.SetCompact(0xff123456);
    BOOST_CHECK_EQUAL(num.GetHex(), "123456000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000");
    BOOST_CHECK_EQUAL(num.GetCompact(), 0xff123456);
}