[FIX] project_template: preserve task end_date

Previously, if multiple tasks in a template project had the same name,
their end_date-values were not copied properly.

project_template/models/project.py

@@ -1,6 +1,9 @@
 # License AGPL-3.0 or later (https://www.gnu.org/licenses/agpl).
 from odoo import api, fields, models
 
+# See _map_tasks_default_valeus
+TASK_DEFAULT_COPY_CONTEXT_KEY = f"{__name__}.task_default_copy_context_key"
+
 
 class Project(models.Model):
     _inherit = "project.project"
@@ -13,17 +16,10 @@ def create_project_from_template(self):
             new_name = self.name.replace(" (TEMPLATE)", " (COPY)")
         else:
             new_name = self.name + " (COPY)"
-        new_project = self.copy(
+        new_project = self.with_context(**{TASK_DEFAULT_COPY_CONTEXT_KEY: True}).copy(
             default={"name": new_name, "active": True, "alias_name": False}
         )
 
-        # SINCE THE END DATE DOESN'T COPY OVER ON TASKS
-        # (Even when changed to copy=true), POPULATE END DATES ON THE TASK
-        for new_task_record in new_project.task_ids:
-            for old_task_record in self.task_ids:
-                if new_task_record.name == old_task_record.name:
-                    new_task_record.date_end = old_task_record.date_end
-
         # OPEN THE NEWLY CREATED PROJECT FORM
         return {
             "view_type": "form",
@@ -34,6 +30,15 @@ def create_project_from_template(self):
             "type": "ir.actions.act_window",
         }
 
+    @api.model
+    def _map_tasks_default_valeus(self, task, project):
+        defaults = super()._map_tasks_default_valeus(task, project)
+        if self.env.context.get(TASK_DEFAULT_COPY_CONTEXT_KEY):
+            # date_end normally is not copied on tasks when a project is
+            # copied, but we want it when generating from template
+            defaults["date_end"] = task.date_end
+        return defaults
+
     # ADD "(TEMPLATE)" TO THE NAME WHEN PROJECT IS MARKED AS A TEMPLATE
     @api.onchange("is_template")
     def on_change_is_template(self):

project_template/tests/test_project_template.py

@@ -1,5 +1,6 @@
 # Copyright 2019 Patrick Wilson <[email protected]>
 # License AGPL-3.0 or later (https://www.gnu.org/licenses/agpl).
+from datetime import datetime, timedelta
 
 from odoo.tests import common
 
@@ -15,9 +16,14 @@ def setUp(self):
                 "partner_id": self.test_customer.id,
             }
         )
-        self.env["project.task"].create(
-            {"name": "TestTask", "project_id": self.test_project.id}
-        )
+        self.tasks = [
+            self.env["project.task"].create(
+                {"name": "TestTask", "project_id": self.test_project.id}
+            ),
+            self.env["project.task"].create(
+                {"name": "TestTask2", "project_id": self.test_project.id}
+            ),
+        ]
 
     # TEST 01: Set project to be a template and test name change
     def test_on_change_is_template(self):
@@ -61,3 +67,30 @@ def test_create_project_from_template_non_standard_name(self):
             [("name", "=", "TestProject(TEST) (COPY)")]
         )
         self.assertEqual(len(new_project), 1)
+
+    def test_create_project_from_template_duplicate_task_names(self):
+        project_01 = self.test_project
+        project_01.is_template = True
+        project_01.on_change_is_template()
+        # Set the same name on all tasks
+        dates = set()
+        now = datetime.now()
+        for i, task in enumerate(self.tasks):
+            date = now - timedelta(weeks=i)
+            task.name = "Same for all tasks"
+            dates.add(date)
+            task.date_end = date
+
+        # Create new Project from Template
+        project_01.create_project_from_template()
+        new_project = self.env["project.project"].search(
+            [("name", "=", "TestProject (COPY)")]
+        )
+        self.assertEqual(len(new_project), 1)
+        new_tasks = self.env["project.task"].search(
+            [
+                ("project_id", "=", new_project.id),
+            ]
+        )
+        self.assertEqual(len(new_tasks), len(self.tasks))
+        self.assertEqual(set(new_tasks.mapped("date_end")), dates)