add merkle digest tests

tests/codex/merkletree/testmerkledigest.nim

@@ -0,0 +1,56 @@
+import std/unittest
+import std/sequtils
+import std/random
+
+import pkg/constantine/math/arithmetic
+
+import pkg/poseidon2
+import pkg/poseidon2/io
+import pkg/poseidon2/sponge
+
+import pkg/questionable/results
+
+import pkg/codex/merkletree
+import pkg/codex/utils/digest
+
+suite "Digest - MerkleTree":
+
+  const KB = 1024
+
+  test "Hashes chunks of data with sponge, and combines them in merkle root":
+    let bytes = newSeqWith(64*KB, rand(byte))
+    var leaves: seq[Poseidon2Hash]
+    for i in 0..<32:
+      let
+        chunk = bytes[(i*2*KB)..<((i+1)*2*KB)]
+        digest = Sponge.digest(chunk, rate = 2)
+      leaves.add(digest)
+
+    let
+      digestTree = Poseidon2MerkleTree.digest(bytes, chunkSize = 2*KB).tryGet
+      tree = Poseidon2MerkleTree.init(leaves).tryGet
+      root = tree.root.tryGet
+      expected = digestTree.root.tryGet
+
+    check bool( root == expected )
+
+  test "Handles partial chunk at the end":
+
+    let bytes = newSeqWith(63*KB, rand(byte))
+    var leaves: seq[Poseidon2Hash]
+    for i in 0..<31:
+      let
+        chunk = bytes[(i*2*KB)..<((i+1)*2*KB)]
+        digest = Sponge.digest(chunk, rate = 2)
+      leaves.add(digest)
+
+    let partialChunk = bytes[(62*KB)..<(63*KB)]
+    leaves.add(Sponge.digest(partialChunk, rate = 2))
+
+    let
+      digestTree = Poseidon2MerkleTree.digest(bytes, chunkSize = 2*KB).tryGet
+      tree = Poseidon2MerkleTree.init(leaves).tryGet
+      root = tree.root.tryGet
+      expected = digestTree.root.tryGet
+
+    check bool( root == expected )

tests/codex/testmerkletree.nim

@@ -1,5 +1,6 @@
 import ./merkletree/testcodextree
 import ./merkletree/testposeidon2tree
 import ./merkletree/testcodexcoders
+import ./merkletree/testmerkledigest
 
 {.warning[UnusedImport]: off.}