fix: classify malformed JSON scalar wire payloads

json.go

@@ -194,21 +194,21 @@ func FormatJSONSimpleValue(formatter Formatter, value spanner.GenericColumnValue
 func validateRawJSONValue(code sppb.TypeCode, value *structpb.Value) (string, error) {
 	stringValue, ok := value.GetKind().(*structpb.Value_StringValue)
 	if !ok {
-		return "", fmt.Errorf("invalid %s JSON payload kind %T: want string value", code, value.GetKind())
+		return "", fmt.Errorf("%w: invalid %s JSON payload kind %T: want string value", ErrMalformedWire, code, value.GetKind())
 	}
 
 	switch code {
 	case sppb.TypeCode_INT64, sppb.TypeCode_ENUM:
 		trimmed := strings.TrimSpace(stringValue.StringValue)
 		if !json.Valid([]byte(stringValue.StringValue)) {
-			return "", fmt.Errorf("invalid %s JSON payload %q", code, stringValue.StringValue)
+			return "", fmt.Errorf("%w: invalid %s JSON payload %q", ErrMalformedWire, code, stringValue.StringValue)
 		}
 		if _, err := strconv.ParseInt(trimmed, 10, 64); err != nil {
-			return "", fmt.Errorf("invalid %s JSON payload %q: %w", code, stringValue.StringValue, err)
+			return "", fmt.Errorf("%w: invalid %s JSON payload %q: %w", ErrMalformedWire, code, stringValue.StringValue, err)
 		}
 	case sppb.TypeCode_JSON:
 		if !json.Valid([]byte(stringValue.StringValue)) {
-			return "", fmt.Errorf("invalid %s JSON payload %q", code, stringValue.StringValue)
+			return "", fmt.Errorf("%w: invalid %s JSON payload %q", ErrMalformedWire, code, stringValue.StringValue)
 		}
 	}
 

json_malformed_wire_test.go

@@ -0,0 +1,62 @@
+package spanvalue
+
+import (
+	"errors"
+	"strconv"
+	"testing"
+
+	"cloud.google.com/go/spanner"
+	sppb "cloud.google.com/go/spanner/apiv1/spannerpb"
+	"github.com/google/go-cmp/cmp"
+	"google.golang.org/protobuf/types/known/structpb"
+)
+
+func TestJSONSpecialScalarMalformedWire(t *testing.T) {
+	t.Parallel()
+	for _, code := range []sppb.TypeCode{sppb.TypeCode_BOOL, sppb.TypeCode_INT64, sppb.TypeCode_ENUM, sppb.TypeCode_JSON} {
+		t.Run(code.String(), func(t *testing.T) {
+			t.Parallel()
+			_, err := JSONFormatConfig().FormatToplevelColumn(spanner.GenericColumnValue{Type: &sppb.Type{Code: code}, Value: structpb.NewListValue(&structpb.ListValue{})})
+			if !errors.Is(err, ErrMalformedWire) || errors.Is(err, ErrUnknownType) {
+				t.Errorf("malformed kind classification: %v", err)
+			}
+		})
+	}
+	for _, code := range []sppb.TypeCode{sppb.TypeCode_INT64, sppb.TypeCode_ENUM} {
+		for _, tt := range []struct {
+			wire  string
+			cause error
+		}{{"12.5", strconv.ErrSyntax}, {"9223372036854775808", strconv.ErrRange}} {
+			t.Run(code.String()+"/"+tt.wire, func(t *testing.T) {
+				t.Parallel()
+				_, err := JSONFormatConfig().FormatToplevelColumn(spanner.GenericColumnValue{Type: &sppb.Type{Code: code}, Value: structpb.NewStringValue(tt.wire)})
+				var numErr *strconv.NumError
+				if !errors.Is(err, ErrMalformedWire) || !errors.Is(err, tt.cause) || !errors.As(err, &numErr) {
+					t.Fatalf("error lost classification or parse cause: %v", err)
+				}
+				if numErr.Num != tt.wire {
+					t.Errorf("Num=%q, want %q", numErr.Num, tt.wire)
+				}
+			})
+		}
+	}
+}
+
+func TestJSONSpecialScalarPreservesWire(t *testing.T) {
+	t.Parallel()
+	for _, tt := range []struct {
+		code sppb.TypeCode
+		wire string
+	}{{sppb.TypeCode_INT64, " 42 "}, {sppb.TypeCode_ENUM, "\n-1\t"}, {sppb.TypeCode_JSON, "{\n \"b\":1, \"a\":2\n}"}} {
+		t.Run(tt.code.String(), func(t *testing.T) {
+			t.Parallel()
+			got, err := JSONFormatConfig().FormatToplevelColumn(spanner.GenericColumnValue{Type: &sppb.Type{Code: tt.code}, Value: structpb.NewStringValue(tt.wire)})
+			if err != nil {
+				t.Fatal(err)
+			}
+			if diff := cmp.Diff(tt.wire, got); diff != "" {
+				t.Errorf("(-want +got):\n%s", diff)
+			}
+		})
+	}
+}

json_test.go

@@ -152,6 +152,9 @@ func TestJSONFormatConfig_InvalidRawPayload(t *testing.T) {
 			if !strings.Contains(err.Error(), tt.wantErr) {
 				t.Fatalf("error = %q, want substring %q", err, tt.wantErr)
 			}
+			if !errors.Is(err, ErrMalformedWire) {
+				t.Fatalf("error = %v, want ErrMalformedWire", err)
+			}
 		})
 	}
 }