fix: exluded characters in random string generator (#111)

* exluded characters in random string generator

* randomString returning error

* add panic in case of string generation failture

* fix panic for Username

Co-authored-by: o.musin <o.musin@tinkoff.ru>

faker.go

@@ -32,7 +32,10 @@ var (
 	generateUniqueValues = false
 	// Unique values are kept in memory so the generator retries if the value already exists
 	uniqueValues = map[string][]interface{}{}
-	lang         = LangENG
+	// Lang is selected language for random string generator
+	lang = LangENG
+	// How much tries for generating random string
+	maxGenerateStringRetries = 1000000
 )
 
 type numberBoundary struct {
@@ -41,18 +44,19 @@ type numberBoundary struct {
 }
 
 type langRuneBoundary struct {
-	start rune
-	end   rune
+	start   rune
+	end     rune
+	exclude []rune
 }
 
 // Language rune boundaries here
 var (
 	// LangENG is for english language
-	LangENG = langRuneBoundary{65, 122}
+	LangENG = langRuneBoundary{65, 122, []rune{91, 92, 93, 94, 95, 96}}
 	// LangCHI is for chinese language
-	LangCHI = langRuneBoundary{19968, 40869}
+	LangCHI = langRuneBoundary{19968, 40869, nil}
 	// LangRUS is for russian language
-	LangRUS = langRuneBoundary{1025, 1105}
+	LangRUS = langRuneBoundary{1025, 1105, nil}
 )
 
 // Supported tags
@@ -246,9 +250,9 @@ var (
 
 // Compiled regexp
 var (
-	findLangReg *regexp.Regexp
-	findLenReg  *regexp.Regexp
-	findSliceLenReg  *regexp.Regexp
+	findLangReg     *regexp.Regexp
+	findLenReg      *regexp.Regexp
+	findSliceLenReg *regexp.Regexp
 )
 
 func init() {
@@ -479,8 +483,8 @@ func getValue(a interface{}) (reflect.Value, error) {
 		}
 
 	case reflect.String:
-		res := randomString(randomStringLen, &lang)
-		return reflect.ValueOf(res), nil
+		res, err := randomString(randomStringLen, &lang)
+		return reflect.ValueOf(res), err
 	case reflect.Slice:
 		len := randomSliceAndMapSize()
 		if shouldSetNil && len == 0 {
@@ -848,8 +852,8 @@ func extractStringFromTag(tag string) (interface{}, error) {
 		toRet := args[rand.Intn(len(args))]
 		return strings.TrimSpace(toRet), nil
 	}
-	res := randomString(strlen, strlng)
-	return res, nil
+	res, err := randomString(strlen, strlng)
+	return res, err
 }
 
 func extractLangFromTag(tag string) (*langRuneBoundary, error) {
@@ -1046,15 +1050,34 @@ func extractNumberFromText(text string) (int, error) {
 	return strconv.Atoi(texts[1])
 }
 
-func randomString(n int, lang *langRuneBoundary) string {
+func randomString(n int, lang *langRuneBoundary) (string, error) {
 	b := make([]rune, 0)
+	set := make(map[rune]struct{})
+	if lang.exclude != nil {
+		for _, s := range lang.exclude {
+			set[s] = struct{}{}
+		}
+	}
+
+	counter := 0
 	for i := 0; i < n; {
 		randRune := rune(rand.Intn(int(lang.end-lang.start)) + int(lang.start))
+		for slice.ContainsRune(set, randRune) {
+			if counter++; counter >= maxGenerateStringRetries {
+				return "", errors.New("Max number of string generation retries exhausted")
+			}
+			randRune = rune(rand.Intn(int(lang.end-lang.start)) + int(lang.start))
+			_, ok := set[randRune]
+			if !ok {
+				break
+			}
+		}
 		b = append(b, randRune)
 		i++
 	}
 
-	return string(b)
+	k := string(b)
+	return k, nil
 }
 
 // randomIntegerWithBoundary returns a random integer between input start and end boundary. [start, end)

faker_test.go

@@ -21,7 +21,7 @@ const (
 )
 
 var (
-	langCorrectTagsMap = map[langRuneBoundary]string{LangENG: "lang=eng", LangCHI: "lang=chi", LangRUS: "lang=rus"}
+	langCorrectTagsMap = map[string]langRuneBoundary{"lang=eng": LangENG, "lang=chi": LangCHI, "lang=rus": LangRUS}
 	langUncorrectTags  = [3]string{"lang=", "lang", "lng=eng"}
 
 	lenCorrectTags   = [3]string{"len=4", "len=5", "len=10"}
@@ -597,10 +597,10 @@ func TestExtractingLangFromTag(t *testing.T) {
 	var err error
 	var lng *langRuneBoundary
 	for k, v := range langCorrectTagsMap {
-		if lng, err = extractLangFromTag(v); err != nil {
+		if lng, err = extractLangFromTag(k); err != nil {
 			t.Error(err.Error())
 		}
-		if k != *lng {
+		if !reflect.DeepEqual(v, *lng) {
 			t.Errorf("Got %v lang rune range, but expected %v", lng, k)
 		}
 	}

internet.go

@@ -56,20 +56,32 @@ type Networker interface {
 // Internet struct
 type Internet struct{}
 
-func (internet Internet) email() string {
-	return randomString(7, &LangENG) + "@" + randomString(5, &LangENG) + "." + randomElementFromSliceString(tld)
+func (internet Internet) email() (string, error) {
+	var err error
+	var emailName, emailDomain string
+	if emailName, err = randomString(7, &LangENG); err != nil {
+		return "", err
+	}
+	if emailDomain, err = randomString(7, &LangENG); err != nil {
+		return "", err
+	}
+	return (emailName + "@" + emailDomain + "." + randomElementFromSliceString(tld)), nil
 }
 
 // Email generates random email id
 func (internet Internet) Email(v reflect.Value) (interface{}, error) {
-	return internet.email(), nil
+	return internet.email()
 }
 
 // Email get email randomly in string
 func Email() string {
 	return singleFakeData(EmailTag, func() interface{} {
 		i := Internet{}
-		return i.email()
+		r, err := i.email()
+		if err != nil {
+			panic(err.Error())
+		}
+		return r
 	}).(string)
 }
 
@@ -94,59 +106,83 @@ func MacAddress() string {
 	}).(string)
 }
 
-func (internet Internet) domainName() string {
-	return randomString(7, &LangENG) + "." + randomElementFromSliceString(tld)
+func (internet Internet) domainName() (string, error) {
+	domainPart, err := randomString(7, &LangENG)
+	if err != nil {
+		return "", err
+	}
+	return (domainPart + "." + randomElementFromSliceString(tld)), nil
 }
 
 // DomainName generates random domain name
 func (internet Internet) DomainName(v reflect.Value) (interface{}, error) {
-	return internet.domainName(), nil
+	return internet.domainName()
 }
 
 // DomainName get email domain name in string
 func DomainName() string {
 	return singleFakeData(DomainNameTag, func() interface{} {
 		i := Internet{}
-		return i.domainName()
+		d, err := i.domainName()
+		if err != nil {
+			panic(err.Error())
+		}
+		return d
 	}).(string)
 }
 
-func (internet Internet) url() string {
+func (internet Internet) url() (string, error) {
 	format := randomElementFromSliceString(urlFormats)
 	countVerbs := strings.Count(format, "%s")
+	d, err := internet.domainName()
+	if err != nil {
+		return "", nil
+	}
 	if countVerbs == 1 {
-		return fmt.Sprintf(format, internet.domainName())
+		return fmt.Sprintf(format, d), nil
+	}
+	u, err := internet.username()
+	if err != nil {
+		return "", err
 	}
-	return fmt.Sprintf(format, internet.domainName(), internet.username())
+	return fmt.Sprintf(format, d, u), nil
 }
 
 // URL generates random URL standardized in urlFormats const
 func (internet Internet) URL(v reflect.Value) (interface{}, error) {
-	return internet.url(), nil
+	return internet.url()
 }
 
 // URL get Url randomly in string
 func URL() string {
 	return singleFakeData(URLTag, func() interface{} {
 		i := Internet{}
-		return i.url()
+		u, err := i.url()
+		if err != nil {
+			panic(err.Error())
+		}
+		return u
 	}).(string)
 }
 
-func (internet Internet) username() string {
+func (internet Internet) username() (string, error) {
 	return randomString(7, &LangENG)
 }
 
 // UserName generates random username
 func (internet Internet) UserName(v reflect.Value) (interface{}, error) {
-	return internet.username(), nil
+	return internet.username()
 }
 
 // Username get username randomly in string
 func Username() string {
 	return singleFakeData(UserNameTag, func() interface{} {
 		i := Internet{}
-		return i.username()
+		u, err := i.username()
+		if err != nil {
+			panic(err.Error())
+		}
+		return u
 	}).(string)
 }
 
@@ -194,19 +230,23 @@ func IPv6() string {
 	}).(string)
 }
 
-func (internet Internet) password() string {
+func (internet Internet) password() (string, error) {
 	return randomString(50, &LangENG)
 }
 
 // Password returns a hashed password
 func (internet Internet) Password(v reflect.Value) (interface{}, error) {
-	return internet.password(), nil
+	return internet.password()
 }
 
 // Password get password randomly in string
 func Password() string {
 	return singleFakeData(PASSWORD, func() interface{} {
 		i := Internet{}
-		return i.password()
+		p, err := i.password()
+		if err != nil {
+			panic(err.Error())
+		}
+		return p
 	}).(string)
 }

support/slice/helpers.go

@@ -15,6 +15,12 @@ func Contains(slice []string, item string) bool {
 	return ok
 }
 
+// ContainsRune Check item in map rune type
+func ContainsRune(set map[rune]struct{}, item rune) bool {
+	_, ok := set[item]
+	return ok
+}
+
 // ContainsValue check if value exists in slice, no matter its type
 func ContainsValue(slice []interface{}, value interface{}) bool {
 	for _, v := range slice {