added: regex validation rule

regex.go

@@ -0,0 +1,19 @@
+package validator
+
+import "regexp"
+
+const (
+	// Regex represents the rule name which will be used to find the default error message.
+	Regex = "regex"
+	// RegexMsg is the default error message format for fields with the regex validation rule.
+	RegexMsg = "%s is not valid"
+)
+
+// RegexMatches checks the value of s under validation must match the given regular expression.
+func (v *Validator) RegexMatches(s string, pattern string, field, msg string) *Validator {
+	r := regexp.MustCompile(pattern)
+
+	v.Check(r.Match([]byte(s)), field, v.msg(Regex, msg))
+
+	return v
+}

regex_test.go

@@ -0,0 +1,77 @@
+package validator
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestValidator_RegexMatches(t *testing.T) {
+	tests := []struct {
+		name        string
+		field       string
+		value       string
+		pattern     string
+		isPassed    bool
+		message     string
+		expectedMsg string
+	}{
+		{
+			name:        "test an empty string value will fail regex validation",
+			field:       "code",
+			value:       "",
+			pattern:     "^[\\w-\\.]+@([\\w-]+\\.)+[\\w-]{2,4}$",
+			isPassed:    false,
+			message:     "code is not valid",
+			expectedMsg: "code is not valid",
+		},
+		{
+			name:        "test an empty space string value will fail regex validation",
+			field:       "name",
+			value:       " ",
+			pattern:     "^[0-9]{10}$",
+			isPassed:    false,
+			message:     "name is not valid",
+			expectedMsg: "name is not valid",
+		},
+		{
+			name:        "test a wrong string value will fail regex validation",
+			field:       "id",
+			value:       "09377475856",
+			pattern:     "^[0-9]{10}$",
+			isPassed:    false,
+			message:     "id is not valid",
+			expectedMsg: "id is not valid",
+		},
+		{
+			name:        "test a correct string value will pass validation",
+			field:       "id",
+			value:       "1160277052",
+			pattern:     "^[0-9]{10}$",
+			isPassed:    true,
+			message:     "",
+			expectedMsg: "",
+		},
+		{
+			name:        "test a correct email string value will pass validation",
+			field:       "email",
+			value:       "[email protected]",
+			pattern:     "^[\\w-\\.]+@([\\w-]+\\.)+[\\w-]{2,4}$",
+			isPassed:    true,
+			message:     "",
+			expectedMsg: "",
+		},
+	}
+
+	for _, test := range tests {
+		v := New()
+
+		v.RegexMatches(test.value, test.pattern, test.field, test.message)
+
+		assert.Equal(t, test.isPassed, v.IsPassed())
+
+		if !test.isPassed {
+			assert.Equal(t, test.expectedMsg, v.Errors()[test.field])
+		}
+	}
+}

validator.go

@@ -35,6 +35,7 @@ var (
 		Min:       MinMsg,
 		Between:   BetweenMsg,
 		NotExists: NotExistsMsg,
+		Regex:     RegexMsg,
 	}
 
 	// ErrMethodMessageNotFound is the default message when a method does not have any error message on methodToErrorMessage.