Add ISBN validation checker and tests to v2. (#137)

# Describe Request

Add ISBN validation checker and tests to v2.

# Change Type

New code.

v2/isbn.go

@@ -0,0 +1,43 @@
+// Copyright (c) 2023-2024 Onur Cinar.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+// https://github.com/cinar/checker
+
+package v2
+
+import (
+	"reflect"
+	"regexp"
+)
+
+const (
+	// nameISBN is the name of the ISBN check.
+	nameISBN = "isbn"
+)
+
+var (
+	// ErrNotISBN indicates that the given value is not a valid ISBN.
+	ErrNotISBN = NewCheckError("ISBN")
+
+	// isbnRegex is the regular expression for validating ISBN-10 and ISBN-13.
+	isbnRegex = regexp.MustCompile(`^(97(8|9))?\d{9}(\d|X)$`)
+)
+
+// IsISBN checks if the value is a valid ISBN-10 or ISBN-13.
+func IsISBN(value string) (string, error) {
+	if !isbnRegex.MatchString(value) {
+		return value, ErrNotISBN
+	}
+	return value, nil
+}
+
+// checkISBN checks if the value is a valid ISBN-10 or ISBN-13.
+func checkISBN(value reflect.Value) (reflect.Value, error) {
+	_, err := IsISBN(value.Interface().(string))
+	return value, err
+}
+
+// makeISBN makes a checker function for the ISBN checker.
+func makeISBN(_ string) CheckFunc[reflect.Value] {
+	return checkISBN
+}

v2/isbn_test.go

@@ -0,0 +1,76 @@
+// Copyright (c) 2023-2024 Onur Cinar.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+// https://github.com/cinar/checker
+
+package v2_test
+
+import (
+	"fmt"
+	"testing"
+
+	v2 "github.com/cinar/checker/v2"
+)
+
+func ExampleIsISBN() {
+	_, err := v2.IsISBN("9783161484100")
+	if err != nil {
+		fmt.Println(err)
+	}
+}
+
+func TestIsISBNInvalid(t *testing.T) {
+	_, err := v2.IsISBN("invalid-isbn")
+	if err == nil {
+		t.Fatal("expected error")
+	}
+}
+
+func TestIsISBNValid(t *testing.T) {
+	_, err := v2.IsISBN("9783161484100")
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestCheckISBNNonString(t *testing.T) {
+	defer FailIfNoPanic(t, "expected panic")
+
+	type Book struct {
+		ISBN int `checkers:"isbn"`
+	}
+
+	book := &Book{}
+
+	v2.CheckStruct(book)
+}
+
+func TestCheckISBNInvalid(t *testing.T) {
+	type Book struct {
+		ISBN string `checkers:"isbn"`
+	}
+
+	book := &Book{
+		ISBN: "invalid-isbn",
+	}
+
+	_, ok := v2.CheckStruct(book)
+	if ok {
+		t.Fatal("expected error")
+	}
+}
+
+func TestCheckISBNValid(t *testing.T) {
+	type Book struct {
+		ISBN string `checkers:"isbn"`
+	}
+
+	book := &Book{
+		ISBN: "9783161484100",
+	}
+
+	_, ok := v2.CheckStruct(book)
+	if !ok {
+		t.Fatal("expected valid")
+	}
+}

v2/maker.go

@@ -25,6 +25,7 @@ var makers = map[string]MakeCheckFunc{
 	nameIP:           makeIP,
 	nameIPv4:         makeIPv4,
 	nameIPv6:         makeIPv6,
+	nameISBN:         makeISBN,
 	nameMaxLen:       makeMaxLen,
 	nameMinLen:       makeMinLen,
 	nameRequired:     makeRequired,