[IMP] hr_expense: prevent change of employee on line sheet

In case we change the employee on an expense and  in case expense has
sheet which has only one expense_line_ids, then changing the
expense.employee_id triggers changing the sheet.employee_id too.

In case there are more than one expense linked to the report, then we
unlink the expense line from sheet, (so that the user can create a new report).

task - 2890095

closes odoo/odoo#94424

Signed-off-by: Kevin Baptiste <kba@odoo.com>

addons/hr_expense/models/hr_expense.py

@@ -393,7 +393,18 @@ class HrExpense(models.Model):
         if 'reference' in vals:
             if any(not expense.is_ref_editable for expense in self):
                 raise UserError(_('You are not authorized to edit the reference of this expense report.'))
-        return super(HrExpense, self).write(vals)
+        res = super(HrExpense, self).write(vals)
+        if 'employee_id' in vals:
+            # In case expense has sheet which has only one expense_line_ids,
+            # then changing the expense.employee_id triggers changing the sheet.employee_id too.
+            # Otherwise we unlink the expense line from sheet, (so that the user can create a new report).
+            if self.sheet_id:
+                employees = self.sheet_id.expense_line_ids.mapped('employee_id')
+                if len(employees) == 1:
+                    self.sheet_id.write({'employee_id': vals['employee_id']})
+                elif len(employees) > 1:
+                    self.sheet_id = False
+        return res
 
     @api.model
     def get_empty_list_help(self, help_message):

addons/hr_expense/tests/test_expenses.py

@@ -8,6 +8,44 @@ from odoo import fields
 @tagged('-at_install', 'post_install')
 class TestExpenses(TestExpenseCommon):
 
+    def test_expense_sheet_changing_employee(self):
+        """ Test changing an employee on the expense that is linked with the sheet.
+            - In case sheet has only one expense linked with it, than changing an employee
+            on expense should trigger changing an employee on the sheet itself.
+            - In case sheet has more than one expense linked with it, than changing an employee
+            on one of the expenses, should cause unlinking the expense from the sheet."""
+
+        employee = self.env['hr.employee'].create({
+            'name': 'Gabriel Iglesias',
+        })
+
+        expense1 = self.env['hr.expense'].create({
+            'name': 'Dinner with client - Expenses',
+            'employee_id': self.expense_employee.id,
+            'product_id': self.product_a.id,
+            'unit_amount': 350.00,
+        })
+
+        expense2 = self.env['hr.expense'].create({
+            'name': 'Team building at Huy',
+            'employee_id': employee.id,
+            'product_id': self.product_a.id,
+            'unit_amount': 2500.00,
+        })
+
+        expense_sheet = self.env['hr.expense.sheet'].create({
+            'name': 'Expense for Jannette',
+            'employee_id': self.expense_employee.id,
+            'expense_line_ids': expense1,
+        })
+
+        expense1.employee_id = employee
+        self.assertEqual(expense_sheet.employee_id, employee, 'Employee should have changed on the sheet')
+
+        expense_sheet.expense_line_ids |= expense2
+        expense2.employee_id = self.expense_employee.id
+        self.assertEqual(expense2.sheet_id.id, False, 'Sheet should be unlinked from the expense')
+
     def test_expense_sheet_payment_state(self):
         ''' Test expense sheet payment states when partially paid, in payment and paid. '''