[ETCM-533] fix comments

src/it/scala/io/iohk/ethereum/txExecTest/util/DumpChainApp.scala

@@ -2,7 +2,6 @@ package io.iohk.ethereum.txExecTest.util
 
 import java.time.Clock
 import java.util.concurrent.atomic.AtomicReference
-
 import akka.actor.ActorSystem
 import akka.util.ByteString
 import com.typesafe.config.ConfigFactory
@@ -15,6 +14,7 @@ import io.iohk.ethereum.db.storage.pruning.{ArchivePruning, PruningMode}
 import io.iohk.ethereum.db.storage.{AppStateStorage, StateStorage}
 import io.iohk.ethereum.domain.BlockHeader.HeaderExtraFields.HefEmpty
 import io.iohk.ethereum.domain.{Blockchain, UInt256, _}
+import io.iohk.ethereum.jsonrpc.ProofService.{StorageProof, StorageValueProof}
 import io.iohk.ethereum.ledger.{InMemoryWorldStateProxy, InMemoryWorldStateProxyStorage}
 import io.iohk.ethereum.mpt.MptNode
 import io.iohk.ethereum.network.EtcPeerManagerActor.PeerInfo
@@ -150,7 +150,7 @@ class BlockchainMock(genesisHash: ByteString) extends Blockchain {
       rootHash: NodeHash,
       position: BigInt,
       ethCompatibleStorage: Boolean
-  ): (BigInt, Seq[MptNode]) = (BigInt(0), Seq.empty)
+  ): StorageProof = StorageValueProof(position)
 
   override protected def getHashByBlockNumber(number: BigInt): Option[ByteString] = Some(genesisHash)
 

src/main/scala/io/iohk/ethereum/domain/Blockchain.scala

@@ -1,7 +1,6 @@
 package io.iohk.ethereum.domain
 
 import java.util.concurrent.atomic.AtomicReference
-
 import akka.util.ByteString
 import cats.syntax.flatMap._
 import cats.instances.option._
@@ -13,6 +12,7 @@ import io.iohk.ethereum.db.storage._
 import io.iohk.ethereum.db.storage.pruning.PruningMode
 import io.iohk.ethereum.domain
 import io.iohk.ethereum.domain.BlockchainImpl.BestBlockLatestCheckpointNumbers
+import io.iohk.ethereum.jsonrpc.ProofService.{StorageProof, StorageValueProof}
 import io.iohk.ethereum.ledger.{InMemoryWorldStateProxy, InMemoryWorldStateProxyStorage}
 import io.iohk.ethereum.mpt.{MerklePatriciaTrie, MptNode}
 import io.iohk.ethereum.utils.{ByteStringUtils, Logger}
@@ -105,7 +105,7 @@ trait Blockchain {
       rootHash: ByteString,
       position: BigInt,
       ethCompatibleStorage: Boolean
-  ): (BigInt, Seq[MptNode])
+  ): StorageProof
 
   /**
     * Returns the receipts based on a block hash
@@ -313,16 +313,21 @@ class BlockchainImpl(
       rootHash: ByteString,
       position: BigInt,
       ethCompatibleStorage: Boolean
-  ): (BigInt, Seq[MptNode]) = {
-    val defaultValue = BigInt(0)
+  ): StorageProof = {
     val storage: MptStorage = stateStorage.getBackingStorage(0)
     val mpt: MerklePatriciaTrie[BigInt, BigInt] = {
       if (ethCompatibleStorage) domain.EthereumUInt256Mpt.storageMpt(rootHash, storage)
       else domain.ArbitraryIntegerMpt.storageMpt(rootHash, storage)
     }
-    val value = mpt.get(position).getOrElse(defaultValue)
-    val proof = mpt.getProof(position).getOrElse(Seq.empty)
-    (value, proof)
+    val value = mpt.get(position)
+    val proof = mpt.getProof(position)
+
+    (value, proof) match {
+      case (Some(value), Some(proof)) => StorageValueProof(position, value, proof)
+      case (None, Some(proof)) => StorageValueProof(position, proof = proof)
+      case (Some(value), None) => StorageValueProof(position, value)
+      case (None, None) => StorageValueProof(position)
+    }
   }
 
   private def persistBestBlocksData(): Unit = {

src/main/scala/io/iohk/ethereum/jsonrpc/EthProofService.scala

@@ -4,13 +4,7 @@ import akka.util.ByteString
 import cats.implicits._
 import io.iohk.ethereum.consensus.blocks.BlockGenerator
 import io.iohk.ethereum.domain.{Account, Address, Block, Blockchain, UInt256}
-import io.iohk.ethereum.jsonrpc.ProofService.{
-  GetProofRequest,
-  GetProofResponse,
-  ProofAccount,
-  StorageProof,
-  StorageProofKey
-}
+import io.iohk.ethereum.jsonrpc.ProofService.{GetProofRequest, GetProofResponse, ProofAccount, StorageProof, StorageProofKey, StorageValueProof}
 import io.iohk.ethereum.mpt.{MptNode, MptTraversals}
 import monix.eval.Task
 
@@ -30,21 +24,33 @@ object ProofService {
 
   case class GetProofResponse(proofAccount: ProofAccount)
 
-  /** The key used to get the storage slot in its account tree */
-  case class StorageProofKey(v: BigInt) extends AnyVal
-
+  trait StorageProof {
+    val key: StorageProofKey
+    val value: BigInt
+    val proof: Seq[ByteString]
+  }
   /**
     * Object proving a relationship of a storage value to an account's storageHash
     *
     * @param key   storage proof key
     * @param value the value of the storage slot in its account tree
     * @param proof the set of node values needed to traverse a patricia merkle tree (from root to leaf) to retrieve a value
     */
-  case class StorageProof(
+  case class StorageValueProof(
       key: StorageProofKey,
       value: BigInt,
-      proof: Seq[ByteString]
-  )
+      proof: Seq[ByteString]) extends StorageProof
+
+  object StorageValueProof {
+    def apply(key: BigInt, value: BigInt = BigInt(0), proof: => Seq[MptNode] = Seq.empty[MptNode]): StorageValueProof =
+      new StorageValueProof(StorageProofKey(key), value, proof.map(asRlpSerializedNode))
+
+    def asRlpSerializedNode(node: MptNode): ByteString =
+      ByteString(MptTraversals.encodeNode(node))
+  }
+
+  /** The key used to get the storage slot in its account tree */
+  case class StorageProofKey(v: BigInt) extends AnyVal
 
   /**
     * The merkle proofs of the specified account connecting them to the blockhash of the block specified.
@@ -143,7 +149,7 @@ class EthProofService(blockchain: Blockchain, blockGenerator: BlockGenerator, et
         blockchain.getAccountProof(address, blockNumber).map(_.map(asRlpSerializedNode)),
         noAccountProof(address, blockNumber)
       )
-      storageProof <- Either.right(getStorageProof(account, storageKeys))
+      storageProof = getStorageProof(account, storageKeys)
     } yield ProofAccount(account, accountProof, storageProof, address)
   }
 
@@ -158,9 +164,7 @@ class EthProofService(blockchain: Blockchain, blockGenerator: BlockGenerator, et
             rootHash = account.storageRoot,
             position = storageKey.v,
             ethCompatibleStorage = ethCompatibleStorage
-          ) match {
-        case (value, proof) => StorageProof(storageKey, value, proof.map(asRlpSerializedNode))
-        }
+          )
       }
   }
 

src/test/scala/io/iohk/ethereum/domain/BlockchainSpec.scala

@@ -165,6 +165,24 @@ class BlockchainSpec extends AnyFlatSpec with Matchers with ScalaCheckPropertyCh
     }
   }
 
+  it should "return proof for non-existent account" in new EphemBlockchainTestSetup {
+    val emptyMpt = MerklePatriciaTrie[Address, Account](
+      storagesInstance.storages.stateStorage.getBackingStorage(0)
+    )
+    val mptWithAcc = emptyMpt.put(Address(42), Account.empty(UInt256(7)))
+
+    val headerWithAcc = Fixtures.Blocks.ValidBlock.header.copy(stateRoot = ByteString(mptWithAcc.getRootHash))
+
+    blockchain.storeBlockHeader(headerWithAcc).commit()
+
+    val wrongAddress = Address(666)
+    val retrievedAccountProofWrong = blockchain.getAccountProof(wrongAddress, headerWithAcc.number)
+    //the account doesn't exist, so we can't retrieve it, but we do receive a proof of non-existence with a full path of nodes that we iterated
+    retrievedAccountProofWrong.isDefined shouldBe true
+    retrievedAccountProofWrong.size shouldBe 1
+    mptWithAcc.get(wrongAddress) shouldBe None
+  }
+
   it should "return correct best block number after applying and rollbacking blocks" in new TestSetup {
     forAll(intGen(min = 1: Int, max = maxNumberBlocksToImport)) { numberBlocksToImport =>
       val testSetup = newSetup()

src/test/scala/io/iohk/ethereum/jsonrpc/JsonRpcControllerEthSpec.scala

@@ -18,7 +18,7 @@ import io.iohk.ethereum.jsonrpc.ProofService.{
   GetProofRequest,
   GetProofResponse,
   ProofAccount,
-  StorageProof,
+  StorageValueProof,
   StorageProofKey
 }
 import io.iohk.ethereum.jsonrpc.serialization.JsonSerializers.{
@@ -835,7 +835,7 @@ class JsonRpcControllerEthSpec
         nonce = 0,
         storageHash = ByteString(Hex.decode("1a2b3c")),
         storageProof = Seq(
-          StorageProof(
+          StorageValueProof(
             key = StorageProofKey(42),
             value = BigInt(2000),
             proof = Seq(

src/test/scala/io/iohk/ethereum/mpt/MerklePatriciaTrieSuite.scala

@@ -573,6 +573,7 @@ class MerklePatriciaTrieSuite extends AnyFunSuite with ScalaCheckPropertyChecks
       val proof: Option[Vector[MptNode]] = trie.getProof(key4)
       // then
       assert(proof.isDefined)
+      assert(proof.get.nonEmpty)
   }
 
   test("getProof returns valid proof for existing key") {