fix(hasher): Fix chunk count in merkleizeImpl (#147)

* fixed chunk count

* space

* add test

hasher.go

@@ -341,7 +341,10 @@ func getDepth(d uint64) uint8 {
 }
 
 func (h *Hasher) merkleizeImpl(dst []byte, input []byte, limit uint64) []byte {
-	count := uint64(len(input) / 32)
+	// count is the number of 32 byte chunks from the input, after right-padding
+	// with zeroes to the next multiple of 32 bytes when the input is not aligned
+	// to a multiple of 32 bytes.
+	count := uint64((len(input) + 31) / 32)
 	if limit == 0 {
 		limit = count
 	} else if count > limit {

sszgen/testcases/container.go

@@ -0,0 +1,7 @@
+package testcases
+
+//go:generate go run ../main.go --path container.go
+
+type Vec struct {
+	Values []uint64 `ssz-size:"6"`
+}

sszgen/testcases/container_test.go

@@ -0,0 +1,25 @@
+package testcases
+
+import (
+	"bytes"
+	"testing"
+)
+
+func TestVectorContainer(t *testing.T) {
+	v := &Vec{
+		Values: []uint64{1, 2, 3, 4, 5, 6},
+	}
+	expectedHash := [32]byte{
+		0xac, 0x13, 0x6e, 0xdd, 0xa3, 0xbd, 0xd2, 0xe9,
+		0x49, 0xa1, 0x9a, 0x94, 0x5b, 0x1a, 0xc5, 0x54,
+		0xe4, 0xb6, 0x07, 0xd3, 0x39, 0xa4, 0x3c, 0x54,
+		0x0c, 0x33, 0x60, 0x98, 0xff, 0xf9, 0x7f, 0x2b,
+	}
+	h, err := v.HashTreeRoot()
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !bytes.Equal(h[:], expectedHash[:]) {
+		t.Fatalf("hash mismatch")
+	}
+}