Fixed broken block when data is chunked by block len

When the next chunk of data has size less than block len, but block is
started, it finalized block to early that cause a wrong hash.

Fixed https://github.com/catap/scala-blake3/issues/1

Author: catap

CHANGELOG.md

@@ -3,6 +3,7 @@
 All notable changes to this project will be documented in this file.
 
 ## [unreleased]
+- Fixed an issue when chunked data by block len produced incorrect block.
 
 ## [2.5.2] - 2021-05-17
 - Switch to scala 3.0.0.

shared/src/main/scala/ky/korins/blake3/ChunkState.scala

@@ -72,8 +72,9 @@ private[blake3] class ChunkState(
   def update(bytes: Array[Byte], from: Int, to: Int): Unit = {
     var i = from
 
-    var consume = Math.min(BLOCK_LEN - blockLen, to - i)
-    if (consume < BLOCK_LEN) {
+    val available = BLOCK_LEN - blockLen
+    var consume = Math.min(available, to - i)
+    if (consume < available) {
       System.arraycopy(bytes, i, block, blockLen, consume)
       blockLen += consume
       i += consume

shared/src/test/scala/ky/korins/blake3/Blake3Test.scala

@@ -13,6 +13,7 @@ import org.scalatest.matchers.should
 import org.scalatest.wordspec.AnyWordSpec
 
 import scala.language.implicitConversions
+import scala.util.Random
 
 class Blake3Test extends AnyWordSpec with should.Matchers {
   "Very naive test" in {
@@ -221,4 +222,36 @@ class Blake3Test extends AnyWordSpec with should.Matchers {
       len -= CHUNK_LEN
     }
   }
+
+  "Chunking data" when {
+    "63 bytes" in {
+      val bytes = new Array[Byte](63)
+      Random.nextBytes(bytes)
+      val hasher1 = Blake3.newHasher()
+      hasher1.update(bytes)
+      val expected = hasher1.doneHex(16)
+
+      val hasher2 = Blake3.newHasher()
+      hasher2.update(bytes, 0, 32)
+      hasher2.update(bytes, 32, 31)
+      val actual = hasher2.doneHex(16)
+
+      expected shouldBe actual
+    }
+
+    "64 bytes" in {
+      val bytes = new Array[Byte](64)
+      Random.nextBytes(bytes)
+      val hasher1 = Blake3.newHasher()
+      hasher1.update(bytes, 0, 64)
+      val expected = hasher1.doneHex(16)
+
+      val hasher2 = Blake3.newHasher()
+      hasher2.update(bytes, 0, 32)
+      hasher2.update(bytes, 32, 32)
+      val actual = hasher2.doneHex(16)
+
+      expected shouldBe actual
+    }
+  }
 }