Fix 404 links in GH status for PR builds (#12563)

When a PR build is skipped (exit code 183), it reports SUCCESS to GitHub
so the PR can be merged, but the version is never marked as built. This
caused the status link to point to a 404 "edit version" page.

Author: ericholscher

readthedocs/builds/models.py

@@ -342,13 +342,23 @@ def get_absolute_url(self):
         """
         Get the absolute URL to the docs of the version.
 
-        If the version doesn't have a successfully uploaded build, then we return the project's
-        dashboard page.
+        For external versions (PR builds), if the version is not built, we return the
+        build detail page since these versions are ephemeral and read-only.
+
+        For internal versions, if not built, we return the project's version dashboard page.
 
         Because documentation projects can be hosted on separate domains, this function ALWAYS
         returns with a full "http(s)://<domain>/" prefix.
         """
         if not self.built and not self.uploaded:
+            # External versions (PR builds) should link to the build detail page
+            # since they're read-only and we can't "edit" them
+            if self.type == EXTERNAL:
+                latest_build = self.latest_build
+                if latest_build:
+                    return latest_build.get_full_url()
+
+            # For internal versions, fall back to the project version detail page
             # TODO: Stop assuming protocol based on settings.DEBUG
             # (this pattern is also used in builds.tasks for sending emails)
             protocol = "http" if settings.DEBUG else "https"

readthedocs/rtd_tests/tests/test_oauth.py

@@ -983,6 +983,47 @@ def test_send_build_status_success(self, request):
             "target_url": f"http://{self.project.slug}.readthedocs.io/en/latest/",
         }
 
+    @requests_mock.Mocker(kw="request")
+    def test_send_build_status_success_when_not_built(self, request):
+        """Test that when status is SUCCESS but version is not built, it links to build detail page.
+
+        This is specifically for external versions (PR builds) which are read-only and should
+        always link to the build detail page when not built.
+        """
+        commit = "1234abc"
+        # Create an external version (PR build) that is not built
+        version = get(Version, project=self.project, type=EXTERNAL, built=False)
+        build = get(
+            Build,
+            project=self.project,
+            version=version,
+        )
+        request.post(
+            f"{self.api_url}/app/installations/1111/access_tokens",
+            json=self._get_access_token_json(),
+        )
+        request.get(
+            f"{self.api_url}/repositories/{self.remote_repository.remote_id}/commits/{commit}",
+            json=self._get_commit_json(commit=commit),
+        )
+        status_api_request = request.post(
+            f"{self.api_url}/repos/user/repo/statuses/{commit}",
+            json={},
+        )
+
+        service = self.installation.service
+        assert service.send_build_status(
+            build=build, commit=commit, status=BUILD_STATUS_SUCCESS
+        )
+        assert status_api_request.called
+        assert status_api_request.last_request.json() == {
+            "context": f"docs/readthedocs:{self.project.slug}",
+            "description": "Read the Docs build succeeded!",
+            "state": "success",
+            # Should link to build detail page, not version docs
+            "target_url": f"https://readthedocs.org/projects/{self.project.slug}/builds/{build.pk}/",
+        }
+
     @requests_mock.Mocker(kw="request")
     def test_send_build_status_failure(self, request):
         commit = "1234abc"
@@ -1561,6 +1602,38 @@ def test_send_build_status_successful(self, session, mock_logger, mock_structlog
             "GitHub commit status created for project.",
         )
 
+    @mock.patch("readthedocs.oauth.services.github.structlog")
+    @mock.patch("readthedocs.oauth.services.github.log")
+    @mock.patch("readthedocs.oauth.services.github.GitHubService.session")
+    def test_send_build_status_on_pr_builds(self, session, mock_logger, mock_structlog):
+        """Test that when status is SUCCESS but version is not built, it links to build detail page.
+
+        This happens when a build has exit code 183 (skipped) - it reports SUCCESS
+        to GitHub so the PR can be merged, but the version is never marked as built.
+        """
+        # external_version.built is False by default
+        session.post.return_value.status_code = 201
+        success = self.service.send_build_status(
+            build=self.external_build,
+            commit=self.external_build.commit,
+            status=BUILD_STATUS_SUCCESS,
+        )
+
+        self.assertTrue(success)
+        # Verify that the target_url points to the build detail page, not the version docs
+        call_args = mock_structlog.contextvars.bind_contextvars.call_args_list
+        # Find the call with target_url
+        target_url = None
+        for call in call_args:
+            if 'target_url' in call[1]:
+                target_url = call[1]['target_url']
+                break
+
+        self.assertIsNotNone(target_url)
+        # Should link to build detail page, not version URL
+        self.assertIn(f'/projects/{self.project.slug}/builds/{self.external_build.pk}/', target_url)
+        self.assertNotIn('.readthedocs.io', target_url)
+
     @mock.patch("readthedocs.oauth.services.github.structlog")
     @mock.patch("readthedocs.oauth.services.github.log")
     @mock.patch("readthedocs.oauth.services.github.GitHubService.session")