User email must be unique

energy_communities/models/res_partner.py

 import logging
+from odoo.exceptions import ValidationError
 
 from odoo import SUPERUSER_ID, api, fields, models
 
@@ -28,6 +29,15 @@ class ResPartner(models.Model):
         new_partner = super().create(vals)
         return new_partner
 
+    @api.constrains('email')
+    def _check_email(self):
+        count_users = self.env['res.partner'].search_count([
+            ('email', '=', self.email),
+            ('user_ids', '!=', False)
+        ])
+        if self.email and count_users >= 1:
+            raise ValidationError('The email already registered, please use another email!')
+
     def cron_update_company_ids_from_user(self):
         partner_with_users = self.search(
             [("user_ids", "!=", False), ("user_ids.id", "!=", SUPERUSER_ID)]

energy_communities/tests/test_res_users.py

@@ -2,7 +2,7 @@
 from faker import Faker
 from mock import patch
 from odoo.tests import common
-from odoo.exceptions import UserError
+from odoo.exceptions import UserError, ValidationError
 
 
 faker = Faker(locale='es_ES')
@@ -229,3 +229,25 @@ class TestResUsers(common.TransactionCase):
         self.assertEqual(len(rl_coord), 2)
         self.assertIn(self.coordination, self.coord_admin.company_ids)
         self.assertIn(other_coord, self.coord_admin.company_ids)
+
+    @patch("odoo.addons.energy_communities.models.res_users.ResUsers.create_users_on_keycloak")
+    @patch("odoo.addons.energy_communities.models.res_users.ResUsers.send_reset_password_mail")
+    def test__email_must_be_unique(
+        self, reset_password_mocked, create_kc_user_mocked
+    ):
+        self.users_model.create_energy_community_base_user(
+            vat=faker.vat_id(),
+            first_name="Tom",
+            last_name="Bombadil",
+            lang_code="en_US",
+            email="random.mail@somcomunitats.coop",
+        )
+
+        with self.assertRaises(ValidationError):
+            self.users_model.create_energy_community_base_user(
+                vat=faker.vat_id(),
+                first_name="Timmy",
+                last_name="Box",
+                lang_code="en_US",
+                email="random.mail@somcomunitats.coop",
+            )