Error() methods now include offset and have more consistent messages

decode.go

@@ -113,21 +113,26 @@ type UnmarshalTypeError struct {
 }
 
 func (e *UnmarshalTypeError) Error() string {
-	return "json: cannot unmarshal " + e.Value + " into Go value of type " + e.Type.String()
+	return fmt.Sprintf("json: %s at offset %d", e.message(), e.Offset)
+}
+
+func (e *UnmarshalTypeError) message() string {
+	return fmt.Sprintf("cannot unmarshal %s into Go value of type %s", e.Value, e.Type)
 }
 
 // An UnmarshalFieldError describes a JSON object key that
 // led to an unexported (and therefore unwritable) struct field.
 // (No longer used; kept for compatibility.)
-type UnmarshalFieldError struct {
-	Key   string
-	Type  reflect.Type
-	Field reflect.StructField
-}
-
-func (e *UnmarshalFieldError) Error() string {
-	return "json: cannot unmarshal object key " + strconv.Quote(e.Key) + " into unexported field " + e.Field.Name + " of type " + e.Type.String()
-}
+//type UnmarshalFieldError struct {
+//	Key    string
+//	Type   reflect.Type
+//	Field  reflect.StructField
+//	Offset int64 // error occurred after reading Offset bytes
+//}
+//
+//func (e *UnmarshalFieldError) Error() string {
+//	return fmt.Sprintf("json: cannot unmarshal object key %s into unexported field %s of type %s at offset %d", strconv.Quote(e.Key), e.Field.Name, e.Type, e.Offset)
+//}
 
 // An InvalidUnmarshalError describes an invalid argument passed to Unmarshal.
 // (The argument to Unmarshal must be a non-nil pointer.)

decode_test.go

@@ -288,7 +288,7 @@ var unmarshalTests = []unmarshalTest{
 
 	// syntax errors
 	{in: `{"X": "foo", "Y"}`, err: &SyntaxError{"invalid character '}' after object key", 17}},
-	{in: `[1, 2, 3+]`, err: &SyntaxError{"invalid character '+' after array element", 9}},
+	{in: `[1, 2, 3+]`, err: &SyntaxError{"invalid character '+' after array element (expecting comma or ']')", 9}},
 	{in: `{"X":12x}`, err: &SyntaxError{"invalid character 'x' after object key:value pair", 8}, useNumber: true},
 
 	// raw value errors
@@ -1318,7 +1318,7 @@ func TestInvalidUnmarshal(t *testing.T) {
 			continue
 		}
 		if got := err.Error(); got != tt.want {
-			t.Errorf("Unmarshal = %q; want %q", got, tt.want)
+			t.Errorf("got %q; want %q", got, tt.want)
 		}
 	}
 }
@@ -1330,19 +1330,19 @@ var invalidUnmarshalTextTests = []struct {
 	{nil, "json: Unmarshal(nil)"},
 	{struct{}{}, "json: Unmarshal(non-pointer struct {})"},
 	{(*int)(nil), "json: Unmarshal(nil *int)"},
-	{new(net.IP), "json: cannot unmarshal string into Go value of type *net.IP"},
+	{new(net.IP), "json: cannot unmarshal string into Go value of type *net.IP at offset 3"},
 }
 
 func TestInvalidUnmarshalText(t *testing.T) {
 	buf := []byte(`123`)
-	for _, tt := range invalidUnmarshalTextTests {
+	for i, tt := range invalidUnmarshalTextTests {
 		err := Unmarshal(buf, tt.v)
 		if err == nil {
-			t.Errorf("Unmarshal expecting error, got nil")
+			t.Errorf("#%d Unmarshal expecting error, got nil", i)
 			continue
 		}
 		if got := err.Error(); got != tt.want {
-			t.Errorf("Unmarshal = %q; want %q", got, tt.want)
+			t.Errorf("#%d got %q; want %q", i, got, tt.want)
 		}
 	}
 }
@@ -1356,6 +1356,6 @@ func TestDecodeSingleQuoteStringInterface(t *testing.T) {
 	}
 	want := map[string]interface{}{"key": "value"}
 	if !reflect.DeepEqual(got, want) {
-		t.Errorf("Unmarshal = %q; want %q", got, want)
+		t.Errorf("got %q; want %q", got, want)
 	}
 }

json5_test.go

@@ -2,18 +2,18 @@ package json5
 
 import (
 	"encoding/json"
+	"errors"
 	"io/ioutil"
 	"os"
 	"path/filepath"
-	"strings"
 	"testing"
 
 	"github.com/kylelemons/godebug/pretty"
 	"github.com/robertkrimen/otto"
 )
 
 type ErrorSpec struct {
-	At           int
+	At           int64
 	LineNumber   int
 	ColumnNumber int
 	Message      string
@@ -56,73 +56,80 @@ func TestJSON5Decode(t *testing.T) {
 		}
 
 		t.Logf("file: %s", path)
+
 		switch filepath.Ext(path) {
 		case ".json":
 			jd, err := parseJSON()
 			if err != nil {
-				t.Errorf("unexpected error from json decoder: %s", err)
+				t.Errorf("%s\nunexpected error from json decoder: %s", path, err)
 				return nil
 			}
 			j5d, err := parseJSON5()
 			if err != nil {
-				t.Errorf("unexpected error from json5 decoder: %s", err)
+				t.Errorf("%s\nunexpected error from json5 decoder: %s", path, err)
 				return nil
 			}
 			if diff := pretty.Compare(jd, j5d); diff != "" {
-				t.Errorf("data is not equal\n%s", diff)
+				t.Errorf("%s\ndata is not equal\n%s", path, diff)
 				return nil
 			}
 		case ".json5":
 			if _, err := parseJSON(); err == nil {
-				t.Errorf("expected JSON parsing to fail")
+				t.Errorf("%s\nexpected JSON parsing to fail", path)
 				return nil
 			}
 			es5d, err := parseES5()
 			if err != nil {
-				t.Errorf("unexpected error from ES5 decoder: %s", err)
+				t.Errorf("%s\nunexpected error from ES5 decoder: %s", path, err)
 				return nil
 			}
 			j5d, err := parseJSON5()
 			if err != nil {
-				t.Errorf("unexpected error from json5 decoder: %s", err)
+				t.Errorf("%s\nunexpected error from json5 decoder: %s", path, err)
 				return nil
 			}
 			if diff := pretty.Compare(j5d, es5d); diff != "" {
-				t.Errorf("data is not equal\n%s", diff)
+				t.Errorf("%s\ndata is not equal\n%s", path, diff)
 				return nil
 			}
 		case ".js":
 			if _, err := parseJSON(); err == nil {
-				t.Errorf("expected JSON parsing to fail")
+				t.Errorf("%s\nexpected JSON parsing to fail", path)
 				return nil
 			}
 			if _, err := parseES5(); err != nil {
-				t.Errorf("unexected error from ES5 decoder: %s", err)
+				t.Errorf("%s\nunexected error from ES5 decoder: %s", path, err)
 				return nil
 			}
 			if _, err := parseJSON5(); err == nil {
-				t.Errorf("expected JSON5 parsing to fail")
+				t.Errorf("%s\nexpected JSON5 parsing to fail", path)
 				return nil
 			}
 		case ".txt":
 			var expectedErr *ErrorSpec
-			specName := strings.TrimRight(path, filepath.Ext(path)) + ".errorSpec"
+			specName := path[:len(path)-4] + ".errorSpec"
 			specFile, err := os.Open(specName)
 			if err != nil && !os.IsNotExist(err) {
-				t.Errorf("error trying to open errorSpec file %s: %s", specName, err)
+				t.Errorf("%s\nerror trying to open errorSpec file %s: %s", path, specName, err)
 				return nil
 			}
 			if specFile != nil {
-				defer specFile.Close()
 				expectedErr = &ErrorSpec{}
 				if err := NewDecoder(specFile).Decode(expectedErr); err != nil {
-					t.Errorf("error decoding %s: %s", specName, err)
+					specFile.Close()
+					t.Errorf("%s\nerror decoding %s: %s", path, specName, err)
 					return nil
 				}
+				specFile.Close() // not using defer because we're in a long loop
 			}
 			_, err = parseJSON5()
 			if err == nil {
-				t.Errorf("expected JSON5 parsing to fail")
+				t.Errorf("%s\nexpected JSON5 parsing to fail", path)
+				return nil
+			}
+			//if expectedErr != nil && !matchedError(err, expectedErr) {
+			if !matchedError(err, expectedErr) {
+				t.Errorf("%s\nexpected JSON5 error %+v\nbut got: %+v", path, expectedErr, err)
 				return nil
 			}
 		}
@@ -131,6 +138,18 @@ func TestJSON5Decode(t *testing.T) {
 	})
 }
 
+func matchedError(err error, expected *ErrorSpec) bool {
+	var se *SyntaxError
+	if errors.As(err, &se) {
+		return se.msg == expected.Message && se.Offset == expected.At
+	}
+	var ute *UnmarshalTypeError
+	if errors.As(err, &ute) {
+		return ute.message() == expected.Message && ute.Offset == expected.At
+	}
+	return false
+}
+
 // The tests below this comment were found with go-fuzz
 
 func TestQuotedQuote(t *testing.T) {
@@ -146,9 +165,9 @@ func TestQuotedQuote(t *testing.T) {
 }
 
 func TestInvalidNewline(t *testing.T) {
-	expected := "invalid character '\\n' in string literal"
+	expected := "json: invalid character '\\n' in string literal at offset 8"
 	var v interface{}
 	if err := Unmarshal([]byte("{a:'\\\r0\n'}"), &v); err == nil || err.Error() != expected {
-		t.Errorf("expected error %q, got %s", expected, err)
+		t.Errorf("expected error %q, got %q", expected, err)
 	}
 }

scanner.go

@@ -13,7 +13,10 @@ package json5
 // This file starts with two simple examples using the scanner
 // before diving into the scanner itself.
 
-import "strconv"
+import (
+	"fmt"
+	"strconv"
+)
 
 // checkValid verifies that data is valid JSON-encoded data.
 // scan is passed in for use by checkValid to avoid an allocation.
@@ -66,7 +69,7 @@ type SyntaxError struct {
 	Offset int64  // error occurred after reading Offset bytes
 }
 
-func (e *SyntaxError) Error() string { return e.msg }
+func (e *SyntaxError) Error() string { return fmt.Sprintf("json: %s at offset %d", e.msg, e.Offset) }
 
 // A scanner is a JSON scanning state machine.
 // Callers call scan.reset() and then pass bytes in one at a time
@@ -365,7 +368,7 @@ func stateInKeyLiteral(s *scanner, c byte) int {
 		return stateEndValue(s, c)
 	}
 	if !isValidKeyLiteralByte(c) {
-		return s.error(c, "in key literal")
+		return s.error(c, "in key literal when expecting ':' or whitespace")
 	}
 	return scanContinue
 }
@@ -426,7 +429,7 @@ func stateEndValue(s *scanner, c byte) int {
 			s.popParseState()
 			return scanEndArray
 		}
-		return s.error(c, "after array element")
+		return s.error(c, "after array element (expecting comma or ']')")
 	}
 	return s.error(c, "")
 }

testdata/arrays/no-comma-array.errorSpec

@@ -2,5 +2,5 @@
     at: 16,
     lineNumber: 3,
     columnNumber: 5,
-    message: "Expected ']' instead of 'f'"
+    message: "invalid character 'f' after array element (expecting comma or ']')"
 }

testdata/comments/top-level-block-comment.errorSpec

@@ -1,6 +1,6 @@
 {
-    at: 77,
+    at: 76,
     lineNumber: 4,
     columnNumber: 3,
-    message: "Unexpected EOF"
+    message: "unexpected end of JSON input"
 }

testdata/comments/top-level-inline-comment.errorSpec

@@ -1,6 +1,6 @@
 {
-    at: 66,
+    at: 65,
     lineNumber: 1,
     columnNumber: 67,
-    message: "Unexpected EOF"
+    message: "unexpected end of JSON input"
 }

testdata/misc/empty.errorSpec

@@ -0,0 +1,4 @@
+{
+    at: 0,
+    message: "unexpected end of JSON input"
+}

testdata/numbers/hexadecimal-empty.errorSpec

@@ -0,0 +1,4 @@
+{
+    at: 3,
+    message: "invalid character '\\n' in hex number"
+}

testdata/numbers/integer-with-float-exponent.errorSpec

@@ -0,0 +1,4 @@
+{
+    at: 4,
+    message: "invalid character '.' after top-level value"
+}

testdata/numbers/integer-with-hexadecimal-exponent.errorSpec

@@ -0,0 +1,4 @@
+{
+    at: 4,
+    message: "invalid character 'x' after top-level value"
+}

testdata/numbers/integer-with-negative-float-exponent.errorSpec

@@ -0,0 +1,4 @@
+{
+    at: 5,
+    message: "invalid character '.' after top-level value"
+}

testdata/numbers/integer-with-negative-hexadecimal-exponent.errorSpec

@@ -0,0 +1,4 @@
+{
+    at: 5,
+    message: "invalid character 'x' after top-level value"
+}

testdata/numbers/integer-with-positive-float-exponent.errorSpec

@@ -0,0 +1,4 @@
+{
+    at: 5,
+    message: "invalid character '.' after top-level value"
+}

testdata/numbers/integer-with-positive-hexadecimal-exponent.errorSpec

@@ -0,0 +1,4 @@
+{
+    at: 5,
+    message: "invalid character 'x' after top-level value"
+}

testdata/numbers/lone-decimal-point.errorSpec

@@ -0,0 +1,4 @@
+{
+    at: 1,
+    message: "cannot unmarshal number . into Go value of type float64"
+}

testdata/numbers/negative-octal.errorSpec

@@ -0,0 +1,4 @@
+{
+    at: 3,
+    message: "invalid character '1' after top-level value"
+}

testdata/numbers/negative-zero-octal.errorSpec

@@ -0,0 +1,4 @@
+{
+    at: 3,
+    message: "invalid character '0' after top-level value"
+}

testdata/numbers/octal.errorSpec

@@ -0,0 +1,4 @@
+{
+    at: 2,
+    message: "invalid character '1' after top-level value"
+}

testdata/numbers/positive-octal.errorSpec

@@ -0,0 +1,4 @@
+{
+    at: 3,
+    message: "invalid character '1' after top-level value"
+}

testdata/numbers/positive-zero-octal.errorSpec

@@ -0,0 +1,4 @@
+{
+    at: 3,
+    message: "invalid character '0' after top-level value"
+}

testdata/numbers/zero-octal.errorSpec

@@ -0,0 +1,4 @@
+{
+    at: 2,
+    message: "invalid character '0' after top-level value"
+}

testdata/objects/illegal-unquoted-key-number.errorSpec

@@ -2,5 +2,5 @@
     at: 7,
     lineNumber: 2,
     columnNumber: 5,
-    message: "Bad identifier as unquoted key"
+    message: "invalid character '1' looking for beginning of object key"
 }