Implemented support for checkable errors

codec.go

@@ -21,10 +21,7 @@
 
 package uuid
 
-import (
-	"errors"
-	"fmt"
-)
+import "fmt"
 
 // FromBytes returns a UUID generated from the raw byte slice input.
 // It will return an error if the slice isn't 16 bytes long.
@@ -44,8 +41,6 @@ func FromBytesOrNil(input []byte) UUID {
 	return uuid
 }
 
-var errInvalidFormat = errors.New("uuid: invalid UUID format")
-
 func fromHexChar(c byte) byte {
 	switch {
 	case '0' <= c && c <= '9':
@@ -66,21 +61,21 @@ func (u *UUID) Parse(s string) error {
 	case 36: // canonical
 	case 34, 38:
 		if s[0] != '{' || s[len(s)-1] != '}' {
-			return fmt.Errorf("uuid: incorrect UUID format in string %q", s)
+			return fmt.Errorf("%w %q", ErrIncorrectFormatInString, s)
 		}
 		s = s[1 : len(s)-1]
 	case 41, 45:
 		if s[:9] != "urn:uuid:" {
-			return fmt.Errorf("uuid: incorrect UUID format in string %q", s[:9])
+			return fmt.Errorf("%w %q", ErrIncorrectFormatInString, s[:9])
 		}
 		s = s[9:]
 	default:
-		return fmt.Errorf("uuid: incorrect UUID length %d in string %q", len(s), s)
+		return fmt.Errorf("%w %d in string %q", ErrIncorrectLength, len(s), s)
 	}
 	// canonical
 	if len(s) == 36 {
 		if s[8] != '-' || s[13] != '-' || s[18] != '-' || s[23] != '-' {
-			return fmt.Errorf("uuid: incorrect UUID format in string %q", s)
+			return fmt.Errorf("%w %q", ErrIncorrectFormatInString, s)
 		}
 		for i, x := range [16]byte{
 			0, 2, 4, 6,
@@ -92,7 +87,7 @@ func (u *UUID) Parse(s string) error {
 			v1 := fromHexChar(s[x])
 			v2 := fromHexChar(s[x+1])
 			if v1|v2 == 255 {
-				return errInvalidFormat
+				return ErrInvalidFormat
 			}
 			u[i] = (v1 << 4) | v2
 		}
@@ -103,7 +98,7 @@ func (u *UUID) Parse(s string) error {
 		v1 := fromHexChar(s[i])
 		v2 := fromHexChar(s[i+1])
 		if v1|v2 == 255 {
-			return errInvalidFormat
+			return ErrInvalidFormat
 		}
 		u[i/2] = (v1 << 4) | v2
 	}
@@ -175,20 +170,20 @@ func (u *UUID) UnmarshalText(b []byte) error {
 	case 36: // canonical
 	case 34, 38:
 		if b[0] != '{' || b[len(b)-1] != '}' {
-			return fmt.Errorf("uuid: incorrect UUID format in string %q", b)
+			return fmt.Errorf("%w %q", ErrIncorrectFormatInString, b)
 		}
 		b = b[1 : len(b)-1]
 	case 41, 45:
 		if string(b[:9]) != "urn:uuid:" {
-			return fmt.Errorf("uuid: incorrect UUID format in string %q", b[:9])
+			return fmt.Errorf("%w %q", ErrIncorrectFormatInString, b[:9])
 		}
 		b = b[9:]
 	default:
-		return fmt.Errorf("uuid: incorrect UUID length %d in string %q", len(b), b)
+		return fmt.Errorf("%w %d in string %q", ErrIncorrectLength, len(b), b)
 	}
 	if len(b) == 36 {
 		if b[8] != '-' || b[13] != '-' || b[18] != '-' || b[23] != '-' {
-			return fmt.Errorf("uuid: incorrect UUID format in string %q", b)
+			return fmt.Errorf("%w %q", ErrIncorrectFormatInString, b)
 		}
 		for i, x := range [16]byte{
 			0, 2, 4, 6,
@@ -200,7 +195,7 @@ func (u *UUID) UnmarshalText(b []byte) error {
 			v1 := fromHexChar(b[x])
 			v2 := fromHexChar(b[x+1])
 			if v1|v2 == 255 {
-				return errInvalidFormat
+				return ErrInvalidFormat
 			}
 			u[i] = (v1 << 4) | v2
 		}
@@ -210,7 +205,7 @@ func (u *UUID) UnmarshalText(b []byte) error {
 		v1 := fromHexChar(b[i])
 		v2 := fromHexChar(b[i+1])
 		if v1|v2 == 255 {
-			return errInvalidFormat
+			return ErrInvalidFormat
 		}
 		u[i/2] = (v1 << 4) | v2
 	}
@@ -226,7 +221,7 @@ func (u UUID) MarshalBinary() ([]byte, error) {
 // It will return an error if the slice isn't 16 bytes long.
 func (u *UUID) UnmarshalBinary(data []byte) error {
 	if len(data) != Size {
-		return fmt.Errorf("uuid: UUID must be exactly 16 bytes long, got %d bytes", len(data))
+		return fmt.Errorf("%w, got %d bytes", ErrIncorrectByteLength, len(data))
 	}
 	copy(u[:], data)
 

error.go

@@ -0,0 +1,22 @@
+package uuid
+
+type Error string
+
+const (
+	ErrInvalidFormat           = Error("uuid: invalid UUID format")
+	ErrIncorrectFormatInString = Error("uuid: incorrect UUID format in string")
+	ErrIncorrectLength         = Error("uuid: incorrect UUID length")
+	ErrIncorrectByteLength     = Error("uuid: UUID must be exactly 16 bytes long")
+	ErrNoHwAddressFound        = Error("uuid: no HW address found")
+	ErrTypeConvertError        = Error("uuid: cannot convert")
+	ErrInvalidVersion          = Error("uuid:")
+)
+
+func (e Error) Error() string {
+	return string(e)
+}
+
+func (e Error) Is(target error) bool {
+	_, ok := target.(*Error)
+	return ok
+}

error_test.go

@@ -0,0 +1,200 @@
+package uuid
+
+import (
+	"errors"
+	"fmt"
+	"net"
+	"reflect"
+	"testing"
+)
+
+func TestError(t *testing.T) {
+	var e Error
+	tcs := []struct {
+		err            error
+		expected       string
+		expectedTarget error
+	}{
+		{
+			err:            fmt.Errorf("%w sample error: %v", ErrInvalidVersion, 123),
+			expected:       "uuid: sample error: 123",
+			expectedTarget: &e,
+		},
+		{
+			err:            fmt.Errorf("%w", ErrInvalidFormat),
+			expected:       "uuid: invalid UUID format",
+			expectedTarget: ErrInvalidFormat,
+		},
+		{
+			err:            fmt.Errorf("%w %q", ErrIncorrectFormatInString, "test"),
+			expected:       "uuid: incorrect UUID format in string \"test\"",
+			expectedTarget: ErrIncorrectFormatInString,
+		},
+	}
+	for i, tc := range tcs {
+		t.Run(fmt.Sprintf("Test case %d", i), func(t *testing.T) {
+			var e2 Error
+			if !errors.Is(tc.err, &e2) {
+				t.Error("expected error to be of a wrapped type of Error")
+			}
+			if !errors.Is(tc.err, tc.expectedTarget) {
+				t.Errorf("expected error to be of type %v, but was %v", reflect.TypeOf(tc.expectedTarget), reflect.TypeOf(tc.err))
+			}
+			if tc.err.Error() != tc.expected {
+				t.Errorf("expected err.Error() to be '%s' but was '%s'", tc.expected, tc.err.Error())
+			}
+			var uuidErr Error
+			if !errors.As(tc.err, &uuidErr) {
+				t.Error("expected errors.As() to work")
+			}
+		})
+	}
+}
+
+func TestAllErrorMessages(t *testing.T) {
+	tcs := []struct {
+		function string
+		uuidStr  string
+		expected string
+	}{
+		{ // 34 chars - With brackets
+			function: "parse",
+			uuidStr:  "..................................",
+			expected: "uuid: incorrect UUID format in string \"..................................\"",
+		},
+		{ // 41 chars - urn:uuid:
+			function: "parse",
+			uuidStr:  "123456789................................",
+			expected: "uuid: incorrect UUID format in string \"123456789\"",
+		},
+		{ // other
+			function: "parse",
+			uuidStr:  "....",
+			expected: "uuid: incorrect UUID length 4 in string \"....\"",
+		},
+		{ // 36 chars - canonical, but not correct format
+			function: "parse",
+			uuidStr:  "....................................",
+			expected: "uuid: incorrect UUID format in string \"....................................\"",
+		},
+		{ // 36 chars - canonical, invalid data
+			function: "parse",
+			uuidStr:  "xx00ae9e-dae3-459f-ad0e-6b574be3f950",
+			expected: "uuid: invalid UUID format",
+		},
+		{ // Hash like
+			function: "parse",
+			uuidStr:  "................................",
+			expected: "uuid: invalid UUID format",
+		},
+		{ // Hash like, invalid
+			function: "parse",
+			uuidStr:  "xx00ae9edae3459fad0e6b574be3f950",
+			expected: "uuid: invalid UUID format",
+		},
+		{ // Hash like, invalid
+			function: "parse",
+			uuidStr:  "xx00ae9edae3459fad0e6b574be3f950",
+			expected: "uuid: invalid UUID format",
+		},
+	}
+	for i, tc := range tcs {
+		t.Run(fmt.Sprintf("Test case %d", i), func(t *testing.T) {
+			id := UUID{}
+			err := id.Parse(tc.uuidStr)
+			if err == nil {
+				t.Error("expected an error")
+				return
+			}
+			if err.Error() != tc.expected {
+				t.Errorf("unexpected error '%s' != '%s'", err.Error(), tc.expected)
+			}
+			err = id.UnmarshalText([]byte(tc.uuidStr))
+			if err == nil {
+				t.Error("expected an error")
+				return
+			}
+			if err.Error() != tc.expected {
+				t.Errorf("unexpected error '%s' != '%s'", err.Error(), tc.expected)
+			}
+		})
+	}
+
+	// Unmarshal binary
+	id := UUID{}
+	b := make([]byte, 33)
+	expectedErr := "uuid: UUID must be exactly 16 bytes long, got 33 bytes"
+	err := id.UnmarshalBinary([]byte(b))
+	if err == nil {
+		t.Error("expected an error")
+		return
+	}
+	if err.Error() != expectedErr {
+		t.Errorf("unexpected error '%s' != '%s'", err.Error(), expectedErr)
+	}
+
+	// no hw address error
+	netInterfaces = func() ([]net.Interface, error) {
+		return nil, nil
+	}
+	defer func() {
+		netInterfaces = net.Interfaces
+	}()
+	_, err = defaultHWAddrFunc()
+	if err == nil {
+		t.Error("expected an error")
+		return
+	}
+	expectedErr = "uuid: no HW address found"
+	if err.Error() != expectedErr {
+		t.Errorf("unexpected error '%s' != '%s'", err.Error(), expectedErr)
+	}
+
+	// scan error
+	err = id.Scan(123)
+	if err == nil {
+		t.Error("expected an error")
+		return
+	}
+	expectedErr = "uuid: cannot convert int to UUID"
+	if err.Error() != expectedErr {
+		t.Errorf("unexpected error '%s' != '%s'", err.Error(), expectedErr)
+	}
+
+	// UUId V1 Version
+	id = FromStringOrNil("e86160d3-beff-443c-b9b5-1f8197ccb12e")
+	_, err = TimestampFromV1(id)
+	if err == nil {
+		t.Error("expected an error")
+		return
+	}
+	expectedErr = "uuid: e86160d3-beff-443c-b9b5-1f8197ccb12e is version 4, not version 1"
+	if err.Error() != expectedErr {
+		t.Errorf("unexpected error '%s' != '%s'", err.Error(), expectedErr)
+	}
+
+	// UUId V2 Version
+	id = FromStringOrNil("e86160d3-beff-443c-b9b5-1f8197ccb12e")
+	_, err = TimestampFromV6(id)
+	if err == nil {
+		t.Error("expected an error")
+		return
+	}
+	expectedErr = "uuid: e86160d3-beff-443c-b9b5-1f8197ccb12e is version 4, not version 6"
+	if err.Error() != expectedErr {
+		t.Errorf("unexpected error '%s' != '%s'", err.Error(), expectedErr)
+	}
+
+	// UUId V7 Version
+	id = FromStringOrNil("e86160d3-beff-443c-b9b5-1f8197ccb12e")
+	_, err = TimestampFromV7(id)
+	if err == nil {
+		t.Error("expected an error")
+		return
+	}
+	// There is a "bug" in the error message, this should probably be fixed (6 -> 7)
+	expectedErr = "uuid: e86160d3-beff-443c-b9b5-1f8197ccb12e is version 4, not version 6"
+	if err.Error() != expectedErr {
+		t.Errorf("unexpected error '%s' != '%s'", err.Error(), expectedErr)
+	}
+}

generator.go

@@ -26,7 +26,6 @@ import (
 	"crypto/rand"
 	"crypto/sha1"
 	"encoding/binary"
-	"fmt"
 	"hash"
 	"io"
 	"net"
@@ -452,5 +451,5 @@ func defaultHWAddrFunc() (net.HardwareAddr, error) {
 			return iface.HardwareAddr, nil
 		}
 	}
-	return []byte{}, fmt.Errorf("uuid: no HW address found")
+	return []byte{}, ErrNoHwAddressFound
 }

sql.go

@@ -56,7 +56,7 @@ func (u *UUID) Scan(src interface{}) error {
 		return err
 	}
 
-	return fmt.Errorf("uuid: cannot convert %T to UUID", src)
+	return fmt.Errorf("%w %T to UUID", ErrTypeConvertError, src)
 }
 
 // NullUUID can be used with the standard sql package to represent a

uuid.go

@@ -100,7 +100,7 @@ func (t Timestamp) Time() (time.Time, error) {
 // Returns an error if the UUID is any version other than 1.
 func TimestampFromV1(u UUID) (Timestamp, error) {
 	if u.Version() != 1 {
-		err := fmt.Errorf("uuid: %s is version %d, not version 1", u, u.Version())
+		err := fmt.Errorf("%w %s is version %d, not version 1", ErrInvalidVersion, u, u.Version())
 		return 0, err
 	}
 
@@ -121,7 +121,7 @@ func TimestampFromV1(u UUID) (Timestamp, error) {
 // releases until the spec is final.
 func TimestampFromV6(u UUID) (Timestamp, error) {
 	if u.Version() != 6 {
-		return 0, fmt.Errorf("uuid: %s is version %d, not version 6", u, u.Version())
+		return 0, fmt.Errorf("%w %s is version %d, not version 6", ErrInvalidVersion, u, u.Version())
 	}
 
 	hi := binary.BigEndian.Uint32(u[0:4])
@@ -141,7 +141,7 @@ func TimestampFromV6(u UUID) (Timestamp, error) {
 // releases until the spec is final.
 func TimestampFromV7(u UUID) (Timestamp, error) {
 	if u.Version() != 7 {
-		return 0, fmt.Errorf("uuid: %s is version %d, not version 6", u, u.Version())
+		return 0, fmt.Errorf("%w %s is version %d, not version 6", ErrInvalidVersion, u, u.Version())
 	}
 
 	t := 0 |