nimbus-eth2/tests/fuzzing/ssz_fuzzing.nim

import
  testutils/fuzzing, faststreams/inputs, serialization/testing/tracing,
  ../../beacon_chain/ssz,
  ../../beacon_chain/spec/[datatypes, crypto, digest, datatypes]

export
  ssz, datatypes, crypto, digest, fuzzing

template sszFuzzingTest*(T: type) =
  test:
    block:
      let input = unsafeMemoryInput(payload)
      let decoded = try: input.readValue(SSZ, T)
                    except SSZError: break

      if input.len.get > 0:
        # Some unconsumed input remained, this is not a valid test case
        break

      let reEncoded = SSZ.encode(decoded)

      when T isnot SignedBeaconBlock:
        let hash = hash_tree_root(decoded)

      if payload != reEncoded:
        when hasSerializationTracing:
          # Run deserialization again to produce a seriazation trace
          # (this is useful for comparing with the initial deserialization)
          discard SSZ.decode(reEncoded, T)

        echo "Payload with len = ", payload.len
        echo payload
        echo "Re-encoided payload with len = ", reEncoded.len
        echo reEncoded

        when T isnot SignedBeaconBlock:
          echo "HTR: ", hash

        echo repr(decoded)

        doAssert false