diff --git a/CHANGELOG.org b/CHANGELOG.org
index a08ade0..2a49a97 100644
--- a/CHANGELOG.org
+++ b/CHANGELOG.org
@@ -27,4 +27,5 @@
    Update the style of buttons.
 ** 0.3.6 <2023-07-23 Sun>
    Add the circular next methods for Task.
+   Add the tests for circular next methods.
 
diff --git a/tasks/tests.py b/tasks/tests.py
deleted file mode 100644
index ef8d717..0000000
--- a/tasks/tests.py
+++ /dev/null
@@ -1,2 +0,0 @@
-from django.test import TestCase
-
diff --git a/tasks/tests/test_task.py b/tasks/tests/test_task.py
new file mode 100644
index 0000000..bb2bbda
--- /dev/null
+++ b/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")
+