Fix null type handling in readAny (#117)

decode.go

@@ -511,7 +511,7 @@ func readArrayHeader(r *buffer) (length int64, _ error) {
 		}
 		length = int64(binary.BigEndian.Uint32(buf[4:8]))
 	default:
-		return 0, errorErrorf("type code %#02x is not a recognized list type", type_)
+		return 0, errorErrorf("type code %#02x is not a recognized array type", type_)
 	}
 	return length, nil
 }
@@ -568,7 +568,7 @@ func readBinary(r *buffer) ([]byte, error) {
 		}
 		length = int64(binary.BigEndian.Uint32(buf))
 	default:
-		return nil, errorErrorf("type code %#02x is not a recognized string type", type_)
+		return nil, errorErrorf("type code %#02x is not a recognized binary type", type_)
 	}
 
 	buf, ok := r.next(length)
@@ -579,6 +579,10 @@ func readBinary(r *buffer) ([]byte, error) {
 }
 
 func readAny(r *buffer) (interface{}, error) {
+	if tryReadNull(r) {
+		return nil, nil
+	}
+
 	type_, err := r.peekType()
 	if err != nil {
 		return nil, errorNew("invalid length")

encode.go

@@ -42,6 +42,8 @@ type marshaler interface {
 
 func marshal(wr *buffer, i interface{}) error {
 	switch t := i.(type) {
+	case nil:
+		wr.writeByte(byte(typeCodeNull))
 	case bool:
 		if t {
 			wr.writeByte(byte(typeCodeBoolTrue))

marshal_test.go

@@ -188,13 +188,22 @@ func TestMarshalUnmarshal(t *testing.T) {
 				}
 			}
 
+			// handle special case around nil type
+			if type_ == nil {
+				err = unmarshal(&buf, nil)
+				if err != nil {
+					t.Fatal(fmt.Sprintf("%+v", err))
+					return
+				}
+				return
+			}
+
 			newType := reflect.New(reflect.TypeOf(type_))
 			err = unmarshal(&buf, newType.Interface())
 			if err != nil {
 				t.Fatal(fmt.Sprintf("%+v", err))
 				return
 			}
-
 			cmpType := reflect.Indirect(newType).Interface()
 			if !testEqual(type_, cmpType) {
 				t.Errorf("Roundtrip produced different results:\n %s", testDiff(type_, cmpType))
@@ -537,6 +546,7 @@ var (
 	}
 
 	generalTypes = []interface{}{
+		nil,
 		UUID{1, 2, 3, 4, 5, 6, 7, 8, 10, 11, 12, 13, 14, 15, 16},
 		bool(true),
 		int8(math.MaxInt8),