Take hash test inputs as hex strings. Add MD5 tests.

#[cfg(test)]

mod tests {

    use hex::FromHex;

    use hex::ToHex;

    struct HashTest {

        input: ~[u8],

        expected_output: ~str

    }

    fn HashTest(input: ~str, output: ~str) -> HashTest {

        HashTest { input: input.from_hex(),

                   expected_output: output }

    }

    fn hash_test(hashtype: HashType, hashtest: &HashTest) {

        let calced_raw = hash(hashtype, hashtest.input);

        let calced = calced_raw.to_hex();

        if calced != hashtest.expected_output {

            io::println(fmt!("Test failed - %s != %s", calced, hashtest.expected_output));

        }

        assert calced == hashtest.expected_output;

    }

    // Test vectors from http://www.nsrl.nist.gov/testdata/

    #[test]

    fn test_md5() {

        let s0 = ~[0x61u8, 0x62u8, 0x63u8];

        let d0 = 

           ~[0x90u8, 0x01u8, 0x50u8, 0x98u8, 0x3cu8, 0xd2u8, 0x4fu8, 0xb0u8,

             0xd6u8, 0x96u8, 0x3fu8, 0x7du8, 0x28u8, 0xe1u8, 0x7fu8, 0x72u8];

        assert(hash(MD5, s0) == d0);

        let tests = [

            HashTest(~"", ~"D41D8CD98F00B204E9800998ECF8427E"),

            HashTest(~"7F", ~"83ACB6E67E50E31DB6ED341DD2DE1595"),

            HashTest(~"EC9C", ~"0B07F0D4CA797D8AC58874F887CB0B68"),

            HashTest(~"FEE57A", ~"E0D583171EB06D56198FC0EF22173907"),

            HashTest(~"42F497E0", ~"7C430F178AEFDF1487FEE7144E9641E2"),

            HashTest(~"C53B777F1C", ~"75EF141D64CB37EC423DA2D9D440C925"),

            HashTest(~"89D5B576327B", ~"EBBAF15EB0ED784C6FAA9DC32831BF33"),

            HashTest(~"5D4CCE781EB190", ~"CE175C4B08172019F05E6B5279889F2C"),

            HashTest(~"81901FE94932D7B9", ~"CD4D2F62B8CDB3A0CF968A735A239281"),

            HashTest(~"C9FFDEE7788EFB4EC9", ~"E0841A231AB698DB30C6C0F3F246C014"),

            HashTest(~"66AC4B7EBA95E53DC10B", ~"A3B3CEA71910D9AF56742AA0BB2FE329"),

            HashTest(~"A510CD18F7A56852EB0319", ~"577E216843DD11573574D3FB209B97D8"),

            HashTest(~"AAED18DBE8938C19ED734A8D", ~"6F80FB775F27E0A4CE5C2F42FC72C5F1")];

        for vec::each(tests) |test| {

            hash_test(MD5, test);

        }

    }

    #[test]

    fn test_sha1() {

        let s0 = ~[0x61u8, 0x62u8, 0x63u8];

        let d0 =

           ~[0xa9u8, 0x99u8, 0x3eu8, 0x36u8, 0x47u8, 0x06u8, 0x81u8, 0x6au8,

             0xbau8, 0x3eu8, 0x25u8, 0x71u8, 0x78u8, 0x50u8, 0xc2u8, 0x6cu8,

             0x9cu8, 0xd0u8, 0xd8u8, 0x9du8];

        assert(hash(SHA1, s0) == d0);

        let tests = [

            HashTest(~"616263", ~"A9993E364706816ABA3E25717850C26C9CD0D89D"),

            ];

        for vec::each(tests) |test| {

            hash_test(SHA1, test);

        }

    }

    #[test]

    fn test_sha256() {

        let s0 = ~[0x61u8, 0x62u8, 0x63u8];

        let d0 =

           ~[0xbau8, 0x78u8, 0x16u8, 0xbfu8, 0x8fu8, 0x01u8, 0xcfu8, 0xeau8,

             0x41u8, 0x41u8, 0x40u8, 0xdeu8, 0x5du8, 0xaeu8, 0x22u8, 0x23u8,

             0xb0u8, 0x03u8, 0x61u8, 0xa3u8, 0x96u8, 0x17u8, 0x7au8, 0x9cu8,

             0xb4u8, 0x10u8, 0xffu8, 0x61u8, 0xf2u8, 0x00u8, 0x15u8, 0xadu8];

        assert(hash(SHA256, s0) == d0);

        let tests = [

            HashTest(~"616263", ~"BA7816BF8F01CFEA414140DE5DAE2223B00361A396177A9CB410FF61F20015AD")

            ];

        for vec::each(tests) |test| {

            hash_test(SHA256, test);

        }

    }

}