[FIX] hr_holidays : fix duplicate allocation for batch allocation

STEP TO REPRODUCE :
	1. create a time off type with alloation_validation_type == 'no'
	2. create a batch allocation (with company, department, employee tag or employee mode but with some employees)
	3. records will be duplicated
Expected behaviour : no duplication

task : 3615657

Part-of: odoo/odoo#144394

addons/hr_holidays/models/hr_leave_allocation.py

@@ -708,12 +708,14 @@ class HolidaysAllocation(models.Model):
         } for employee in employees]
 
     def action_validate(self):
-        self.write({
-            'state': 'validate',
-            'approver_id': self.env.user.employee_id.id
-        })
-        self._action_validate_create_childs()
-        self.activity_update()
+        to_validate = self.filtered(lambda alloc: alloc.state != 'validate')
+        if to_validate:
+            to_validate.write({
+                'state': 'validate',
+                'approver_id': self.env.user.employee_id.id
+            })
+            to_validate._action_validate_create_childs()
+            to_validate.activity_update()
         return True
 
     def _action_validate_create_childs(self):

addons/hr_holidays/tests/__init__.py

@@ -20,3 +20,4 @@ from . import test_uninstall
 from . import test_holidays_calendar
 from . import test_negative
 from . import test_past_accruals
+from . import test_allocations

addons/hr_holidays/tests/test_allocations.py

@@ -0,0 +1,91 @@
+# -*- coding: utf-8 -*-
+# Part of Odoo. See LICENSE file for full copyright and licensing details.
+from odoo.tests import tagged
+
+from odoo.addons.hr_holidays.tests.common import TestHrHolidaysCommon
+
+
+@tagged('allocation')
+class TestAllocations(TestHrHolidaysCommon):
+    @classmethod
+    def setUpClass(cls):
+        super(TestAllocations, cls).setUpClass()
+        cls.leave_type = cls.env['hr.leave.type'].create({
+            'name': 'Time Off with no validation for approval',
+            'time_type': 'leave',
+            'requires_allocation': 'yes',
+            'allocation_validation_type': 'no',
+        })
+        cls.department = cls.env['hr.department'].create({
+            'name': 'Test Department',
+        })
+        cls.category_tag = cls.env['hr.employee.category'].create({
+            'name': 'Test category'
+        })
+        cls.employee = cls.env['hr.employee'].create({
+            'name': 'My Employee',
+            'company_id': cls.company.id,
+            'department_id': cls.department.id,
+            'category_ids': [(4, cls.category_tag.id)],
+        })
+
+    def test_allocation_whole_company(self):
+        company_allocation = self.env['hr.leave.allocation'].create({
+            'name': 'Bank Holiday',
+            'holiday_type': 'company',
+            'mode_company_id': self.company.id,
+            'holiday_status_id': self.leave_type.id,
+            'number_of_days': 2,
+            'allocation_type': 'regular',
+        })
+
+        company_allocation.action_validate()
+
+        num_of_allocations = self.env['hr.leave.allocation'].search_count([('employee_id', '=', self.employee.id), ('multi_employee', '=', False)])
+        self.assertEqual(num_of_allocations, 1)
+
+    def test_allocation_multi_employee(self):
+        employee_allocation = self.env['hr.leave.allocation'].create({
+            'name': 'Bank Holiday',
+            'holiday_type': 'employee',
+            'employee_ids': [(4, self.employee.id), (4, self.employee_emp.id)],
+            'employee_id': self.employee.id,
+            'holiday_status_id': self.leave_type.id,
+            'number_of_days': 2,
+            'allocation_type': 'regular',
+        })
+
+        employee_allocation.action_validate()
+
+        num_of_allocations = self.env['hr.leave.allocation'].search_count([('employee_id', '=', self.employee.id), ('multi_employee', '=', False), ('parent_id', '!=', False)])
+        self.assertEqual(num_of_allocations, 1)
+
+    def test_allocation_department(self):
+        department_allocation = self.env['hr.leave.allocation'].create({
+            'name': 'Bank Holiday',
+            'holiday_type': 'department',
+            'department_id': self.department.id,
+            'holiday_status_id': self.leave_type.id,
+            'number_of_days': 2,
+            'allocation_type': 'regular',
+        })
+
+        department_allocation.action_validate()
+
+        num_of_allocations = self.env['hr.leave.allocation'].search_count([('employee_id', '=', self.employee.id), ('multi_employee', '=', False)])
+        self.assertEqual(num_of_allocations, 1)
+
+    def test_allocation_category(self):
+        category_allocation = self.env['hr.leave.allocation'].create({
+            'name': 'Bank Holiday',
+            'holiday_type': 'category',
+            'category_id': self.category_tag.id,
+            'holiday_status_id': self.leave_type.id,
+            'number_of_days': 2,
+            'allocation_type': 'regular',
+        })
+
+        category_allocation.action_validate()
+
+        num_of_allocations = self.env['hr.leave.allocation'].search_count([('employee_id', '=', self.employee.id), ('multi_employee', '=', False)])
+        self.assertEqual(num_of_allocations, 1)