add support for previewing pages

dnscms/tests/test_preview.py

@@ -0,0 +1,37 @@
+"""Round-trip tests for wagtail-headless-preview token resolution via grapple."""
+
+from generic.models import GenericPage
+from tests.conftest import GenericPageFactory
+
+
+def test_generic_page_preview_token_resolves_draft(home_page, graphql_post):
+    """A minted preview token returns the unsaved draft via grapple's page(token: …)."""
+    # Publish a baseline so there's a live revision to diverge from.
+    page = GenericPageFactory(parent=home_page, title="Original title", slug="generic-preview")
+
+    # Mutate in-memory to simulate unsaved editor state, then mint a token.
+    # create_page_preview() snapshots the current to_json() into a PagePreview row.
+    page.title = "Edited title (draft)"
+    preview = page.create_page_preview()
+
+    response, body = graphql_post(
+        """
+        query previewPage($token: String!) {
+          page: page(token: $token) {
+            __typename
+            ... on GenericPage {
+              title
+            }
+          }
+        }
+        """,
+        variables={"token": preview.token},
+    )
+
+    assert response.status_code == 200
+    assert "errors" not in body, body
+    assert body["data"]["page"]["__typename"] == "GenericPage"
+    assert body["data"]["page"]["title"] == "Edited title (draft)"
+
+    # Live revision is unchanged — token short-circuits the published query.
+    assert GenericPage.objects.get(pk=page.pk).title == "Original title"