testutil: fix block generator

testutil/testutil.go

@@ -17,9 +17,9 @@ var prioritySeq int
 // GenerateBlocksOfSize generates a series of blocks of the given byte size
 func GenerateBlocksOfSize(n int, size int64) []blocks.Block {
 	generatedBlocks := make([]blocks.Block, 0, n)
-	buf := make([]byte, size)
 	for i := 0; i < n; i++ {
 		// rand.Read never errors
+		buf := make([]byte, size)
 		rand.Read(buf)
 		b := blocks.NewBlock(buf)
 		generatedBlocks = append(generatedBlocks, b)

testutil/testutil_test.go

@@ -0,0 +1,16 @@
+package testutil
+
+import (
+	"testing"
+
+	blocks "github.com/ipfs/go-block-format"
+)
+
+func TestGenerateBlocksOfSize(t *testing.T) {
+	for _, b1 := range GenerateBlocksOfSize(10, 100) {
+		b2 := blocks.NewBlock(b1.RawData())
+		if b2.Cid() != b1.Cid() {
+			t.Fatal("block CIDs mismatch")
+		}
+	}
+}