📈(backend) capture an event when a comment is created

When a new comment is created, we capture an event related to this comment
creation.

src/backend/core/api/viewsets.py

@@ -3206,7 +3206,14 @@ class CommentViewSet(
     def perform_create(self, serializer):
         """Attach the request user as the comment author."""
         user = self.request.user if self.request.user.is_authenticated else None
-        serializer.save(user=user)
+        comment = serializer.save(user=user)
+
+        posthog_capture(
+            PosthogEventName.COMMENT_CREATED,
+            user,
+            {"comment_id": str(comment.id), "thread_id": str(comment.thread_id)},
+            document=self.get_document_or_404(),
+        )
 
     @drf.decorators.action(
         detail=True,

src/backend/core/tests/documents/test_api_documents_comments.py

@@ -1,6 +1,7 @@
 """Test API for comments on documents."""
 
 import random
+from unittest import mock
 
 from django.contrib.auth.models import AnonymousUser
 
@@ -8,6 +9,7 @@ import pytest
 from rest_framework.test import APIClient
 
 from core import factories, models
+from core.utils.analytics import PosthogEventName
 
 pytestmark = pytest.mark.django_db
 
@@ -184,12 +186,21 @@ def test_create_comment_anonymous_user_public_document():
     )
     thread = factories.ThreadFactory(document=document)
     client = APIClient()
-    response = client.post(
-        f"/api/v1.0/documents/{document.id!s}/threads/{thread.id!s}/comments/",
-        {"body": "test"},
-    )
+    with mock.patch("core.api.viewsets.posthog_capture") as mock_capture:
+        response = client.post(
+            f"/api/v1.0/documents/{document.id!s}/threads/{thread.id!s}/comments/",
+            {"body": "test"},
+        )
     assert response.status_code == 201
 
+    # The comment creation should be tracked in PostHog
+    mock_capture.assert_called_once_with(
+        PosthogEventName.COMMENT_CREATED,
+        None,
+        {"comment_id": response.json()["id"], "thread_id": str(thread.id)},
+        document=document,
+    )
+
     assert response.json() == {
         "id": str(response.json()["id"]),
         "body": "test",
@@ -231,12 +242,21 @@ def test_create_comment_authenticated_user_accessible_document():
     thread = factories.ThreadFactory(document=document)
     client = APIClient()
     client.force_login(user)
-    response = client.post(
-        f"/api/v1.0/documents/{document.id!s}/threads/{thread.id!s}/comments/",
-        {"body": "test"},
-    )
+    with mock.patch("core.api.viewsets.posthog_capture") as mock_capture:
+        response = client.post(
+            f"/api/v1.0/documents/{document.id!s}/threads/{thread.id!s}/comments/",
+            {"body": "test"},
+        )
     assert response.status_code == 201
 
+    # The comment creation should be tracked in PostHog
+    mock_capture.assert_called_once_with(
+        PosthogEventName.COMMENT_CREATED,
+        user,
+        {"comment_id": response.json()["id"], "thread_id": str(thread.id)},
+        document=document,
+    )
+
     assert response.json() == {
         "id": str(response.json()["id"]),
         "body": "test",

src/backend/core/utils/analytics.py

@@ -29,6 +29,9 @@ class PosthogEventName(StrEnum):
     # Thread
     THREAD_CREATED = "thread_created"
 
+    # Comment
+    COMMENT_CREATED = "comment_created"
+
     # User
     USER_LOGIN = "user_login"