diff --git a/realworld/comments/tests.py b/realworld/comments/tests.py
index e477576..183646a 100644
--- a/realworld/comments/tests.py
+++ b/realworld/comments/tests.py
@@ -40,3 +40,133 @@ def test_add_comment(self):
 
         self.assertEqual(comment.article, self.article)
         self.assertEqual(comment.author, self.author)
+
+    def test_add_comment_invalid_form(self):
+        self.client.force_login(self.author)
+
+        response = self.client.post(self.url, {"content": ""})
+        self.assertEqual(response.status_code, http.HTTPStatus.OK)
+        
+        self.assertFalse(Comment.objects.exists())
+        self.assertTrue(response.context["form"].errors)
+
+
+class TestEditCommentView(TestCase):
+
+    @classmethod
+    def setUpTestData(cls):
+        cls.author = User(
+            email="tester@gmail.com",
+            name="tester",
+        )
+        cls.author.save()
+
+        cls.other_user = User(
+            email="other@gmail.com",
+            name="other",
+        )
+        cls.other_user.save()
+
+        cls.article = Article.objects.create(
+            title="test",
+            summary="test",
+            content="test",
+            author=cls.author,
+        )
+
+        cls.comment = Comment.objects.create(
+            content="original content",
+            author=cls.author,
+            article=cls.article,
+        )
+
+        cls.url = reverse("edit_comment", args=[cls.comment.id])
+
+    def test_edit_comment_get(self):
+        self.client.force_login(self.author)
+
+        response = self.client.get(self.url)
+        self.assertEqual(response.status_code, http.HTTPStatus.OK)
+        self.assertContains(response, "original content")
+        self.assertEqual(response.context["comment"], self.comment)
+
+    def test_edit_comment_post_valid(self):
+        self.client.force_login(self.author)
+
+        response = self.client.post(self.url, {"content": "updated content"})
+        self.assertEqual(response.status_code, http.HTTPStatus.OK)
+
+        self.comment.refresh_from_db()
+        self.assertEqual(self.comment.content, "updated content")
+
+    def test_edit_comment_post_invalid(self):
+        self.client.force_login(self.author)
+
+        response = self.client.post(self.url, {"content": ""})
+        self.assertEqual(response.status_code, http.HTTPStatus.OK)
+
+        self.comment.refresh_from_db()
+        self.assertEqual(self.comment.content, "original content")
+        self.assertTrue(response.context["form"].errors)
+
+    def test_edit_comment_unauthorized_user(self):
+        self.client.force_login(self.other_user)
+
+        response = self.client.get(self.url)
+        self.assertEqual(response.status_code, http.HTTPStatus.NOT_FOUND)
+
+        response = self.client.post(self.url, {"content": "hacked content"})
+        self.assertEqual(response.status_code, http.HTTPStatus.NOT_FOUND)
+
+        self.comment.refresh_from_db()
+        self.assertEqual(self.comment.content, "original content")
+
+
+class TestDeleteCommentView(TestCase):
+
+    @classmethod
+    def setUpTestData(cls):
+        cls.author = User(
+            email="tester@gmail.com",
+            name="tester",
+        )
+        cls.author.save()
+
+        cls.other_user = User(
+            email="other@gmail.com",
+            name="other",
+        )
+        cls.other_user.save()
+
+        cls.article = Article.objects.create(
+            title="test",
+            summary="test",
+            content="test",
+            author=cls.author,
+        )
+
+        cls.comment = Comment.objects.create(
+            content="test content",
+            author=cls.author,
+            article=cls.article,
+        )
+
+        cls.url = reverse("delete_comment", args=[cls.comment.id])
+
+    def test_delete_comment(self):
+        self.client.force_login(self.author)
+
+        self.assertTrue(Comment.objects.filter(pk=self.comment.id).exists())
+
+        response = self.client.delete(self.url)
+        self.assertEqual(response.status_code, http.HTTPStatus.OK)
+
+        self.assertFalse(Comment.objects.filter(pk=self.comment.id).exists())
+
+    def test_delete_comment_unauthorized_user(self):
+        self.client.force_login(self.other_user)
+
+        response = self.client.delete(self.url)
+        self.assertEqual(response.status_code, http.HTTPStatus.NOT_FOUND)
+
+        self.assertTrue(Comment.objects.filter(pk=self.comment.id).exists())