reduce diff

Author: Dan Laine

x/merkledb/codec.go

@@ -98,6 +98,7 @@ func (c *codecImpl) encodeDBNode(n *dbNode) []byte {
 		estimatedLen = estimatedValueLen + minVarIntLen + estimatedNodeChildLen*numChildren
 		buf          = bytes.NewBuffer(make([]byte, 0, estimatedLen))
 	)
+
 	c.encodeMaybeByteSlice(buf, n.value)
 	c.encodeUint(buf, uint64(numChildren))
 	// Note we insert children in order of increasing index

x/merkledb/codec_test.go

@@ -71,6 +71,33 @@ func FuzzCodecInt(f *testing.F) {
 	)
 }
 
+func FuzzCodecKey(f *testing.F) {
+	f.Fuzz(
+		func(
+			t *testing.T,
+			b []byte,
+		) {
+			require := require.New(t)
+			codec := codec.(*codecImpl)
+			reader := bytes.NewReader(b)
+			startLen := reader.Len()
+			got, err := codec.decodeKey(reader)
+			if err != nil {
+				t.SkipNow()
+			}
+			endLen := reader.Len()
+			numRead := startLen - endLen
+
+			// Encoding [got] should be the same as [b].
+			var buf bytes.Buffer
+			codec.encodeKey(&buf, got)
+			bufBytes := buf.Bytes()
+			require.Len(bufBytes, numRead)
+			require.Equal(b[:numRead], bufBytes)
+		},
+	)
+}
+
 func FuzzCodecDBNodeCanonical(f *testing.F) {
 	f.Fuzz(
 		func(