Add the tests for circular next methods.

tasks/tests/test_task.py

@@ -0,0 +1,53 @@
+from django.test import TestCase
+from tasks.models import Task, Tasks
+
+class TaskTestCase(TestCase):
+    def setUp(self):
+        statuses = ["TODO", "DOING", "DONE", "CANCELED"]
+        names = [f"Test Task {i}" for i in statuses]
+        description = ""
+
+        tasks = [
+            Task(name=name, description=description, status=status)
+            for name, status in zip(names, statuses)
+        ]
+
+        Task.objects.bulk_create(tasks)
+
+    def test__get_status_index_with_existing(self):
+        task = Task.objects.filter(status="DONE").first()
+        index = task._get_status_index()
+        self.assertEqual(index, 2)
+
+    def test_circular_next_status_index_for_todo(self):
+        task = Task.objects.filter(status="TODO").first()
+        index = task.circular_next_status_index()
+        self.assertEqual(index, 1)
+
+    def test_circular_next_status_index_for_canceled(self):
+        task = Task.objects.filter(status="CANCELED").first()
+        next_index = task.circular_next_status_index()
+        self.assertEqual(next_index, 0)
+
+    def test_circular_next_status_for_todo(self):
+        task = Task.objects.filter(status="TODO").first()
+        next_status = task.circular_next_status()
+        self.assertEqual(next_status, "DOING")
+
+    def test_circular_next_status_for_canceled(self):
+        task = Task.objects.filter(status="CANCELED").first()
+        next_status = task.circular_next_status()
+        self.assertEqual(next_status, "TODO")
+
+    def test_set_circular_next_status_for_todo(self):
+        task = Task.objects.filter(status="TODO").first()
+        task.set_circular_next_status()
+        task.refresh_from_db()
+        self.assertEqual(task.status, "DOING")
+
+    def test_set_circular_next_status_for_canceled(self):
+        task = Task.objects.filter(status="CANCELED").first()
+        task.set_circular_next_status()
+        task.refresh_from_db()
+        self.assertEqual(task.status, "TODO")
+