is: Add possibility to overwrite the email validtion TTL

pkg/identityserver/email_validation_registry.go

@@ -42,7 +42,7 @@ type emailValidationRegistry struct {
 }
 
 func (is *IdentityServer) refreshEmailValidation(
-	ctx context.Context, usrID *ttnpb.UserIdentifiers,
+	ctx context.Context, usrID *ttnpb.UserIdentifiers, opts ...ttnpb.EmailValidationOverwrite,
 ) (*ttnpb.EmailValidation, error) {
 	ttl := is.configFromContext(ctx).UserRegistration.ContactInfoValidation.TokenTTL
 	expires := time.Now().Add(ttl)
@@ -55,6 +55,11 @@ func (is *IdentityServer) refreshEmailValidation(
 			return err
 		}
 		validation.ExpiresAt = timestamppb.New(expires)
+
+		for _, opt := range opts {
+			opt(validation)
+		}
+
 		if err = st.RefreshEmailValidation(ctx, validation); err != nil {
 			return err
 		}
@@ -67,7 +72,7 @@ func (is *IdentityServer) refreshEmailValidation(
 }
 
 func (is *IdentityServer) requestEmailValidation(
-	ctx context.Context, usrID *ttnpb.UserIdentifiers,
+	ctx context.Context, usrID *ttnpb.UserIdentifiers, opts ...ttnpb.EmailValidationOverwrite,
 ) (*ttnpb.EmailValidation, error) {
 	var validation *ttnpb.EmailValidation
 	err := is.store.Transact(ctx, func(ctx context.Context, st store.Store) (err error) {
@@ -98,6 +103,11 @@ func (is *IdentityServer) requestEmailValidation(
 					time.Now().Add(is.configFromContext(ctx).UserRegistration.ContactInfoValidation.TokenTTL),
 				),
 			}
+
+			for _, opt := range opts {
+				opt(validation)
+			}
+
 			validation, err = st.CreateEmailValidation(ctx, validation)
 			if err != nil {
 				// Only one validation can exist at a time, so if it already exists, return a forbidden error.

pkg/ttnpb/email_validation.go

@@ -0,0 +1,28 @@
+// Copyright © 2024 The Things Network Foundation, The Things Industries B.V.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ttnpb
+
+import "google.golang.org/protobuf/types/known/timestamppb"
+
+// EmailValidationOverwrite is a function to overwrite the EmailValidation.
+type EmailValidationOverwrite func(*EmailValidation) *EmailValidation
+
+// EmailValidationWithExpiresAt overwrites the EmailValidation ExpiresAt field.
+func EmailValidationWithExpiresAt(expiresAt *timestamppb.Timestamp) EmailValidationOverwrite {
+	return func(validation *EmailValidation) *EmailValidation {
+		validation.ExpiresAt = expiresAt
+		return validation
+	}
+}