Avoid allocating memory in Type() method.

varint_test.go

@@ -0,0 +1,22 @@
+package cid
+
+import (
+	"encoding/binary"
+	"testing"
+)
+
+func TestUvarintRoundTrip(t *testing.T) {
+	testCases := []uint64{0, 1, 2, 127, 128, 129, 255, 256, 257, 1<<63 - 1}
+	for _, tc := range testCases {
+		buf := make([]byte, 16)
+		binary.PutUvarint(buf, tc)
+		v, l1 := uvarint(string(buf))
+		_, l2 := binary.Uvarint(buf)
+		if tc != v {
+			t.Errorf("roundtrip failed expected %d but got %d", tc, v)
+		}
+		if l1 != l2 {
+			t.Errorf("length incorrect expected %d but got %d", l2, l1)
+		}
+	}
+}