fix(proto): encode nil *uint8 as "0" like other numeric pointers (#3869)

WriteArg encodes a nil pointer to a numeric type as its zero value: every
nil *int*/*uint*/*float*/*bool returns "0". The *uint8 case instead returned
an empty string, which is also inconsistent with its own non-nil path that
writes the number via w.uint. Encode nil *uint8 as "0" and update the table
test assertion.

Co-authored-by: Nedyalko Dyakov <1547186+ndyakov@users.noreply.github.com>

Author: sueun-dev

internal/proto/writer.go

@@ -118,7 +118,7 @@ func (w *Writer) WriteArg(v interface{}) error {
 		return w.uint(uint64(v))
 	case *uint8:
 		if v == nil {
-			return w.string("")
+			return w.uint(0)
 		}
 		return w.uint(uint64(*v))
 	case uint16:

internal/proto/writer_test.go

@@ -137,7 +137,7 @@ var _ = Describe("WriteArg", func() {
 		(*uint)(nil):                           "$1\r\n0\r\n",
 		uint8(10):                              "$2\r\n10\r\n",
 		util.ToPtr(uint8(10)):                  "$2\r\n10\r\n",
-		(*uint8)(nil):                          "$0\r\n\r\n",
+		(*uint8)(nil):                          "$1\r\n0\r\n",
 		uint16(10):                             "$2\r\n10\r\n",
 		util.ToPtr(uint16(10)):                 "$2\r\n10\r\n",
 		(*uint16)(nil):                         "$1\r\n0\r\n",