feat(testutils): fail tests that overflow Postgres's subtransaction cache

pyproject.toml

@@ -349,6 +349,10 @@ filterwarnings = [
   "ignore:The list-based error format for `ListSerializer` is deprecated.*:PendingDeprecationWarning",
 ]
 looponfailroots = ["src", "tests"]
+# Functions whose transactions overflow Postgres's subtransaction cache today. Only remove entries.
+savepoint_baseline = [
+  "src/sentry/backup/imports.py:_import",
+]
 
 [tool.mypy]
 python_version = "3.13"

src/sentry/testutils/cases.py

@@ -205,6 +205,7 @@
     from sentry.models.releaseheadcommit import ReleaseHeadCommit
     from sentry.models.team import Team
     from sentry.replays.lib.event_linking import EventLinkKafkaMessage
+    from sentry.testutils.pytest.savepoints import SavepointUsage
     from sentry.testutils.pytest.stale_database_reads import StaleDatabaseReads
     from sentry.users.services.user import RpcUser
 
@@ -281,6 +282,10 @@ def polyfill_capture_on_commit_callbacks(
     def expose_stale_database_reads(self, stale_database_reads: StaleDatabaseReads) -> None:
         self.stale_database_reads = stale_database_reads
 
+    @pytest.fixture(autouse=True)
+    def expose_savepoint_usage(self, savepoint_usage: SavepointUsage) -> None:
+        self.savepoint_usage = savepoint_usage
+
     def feature(
         self, names: str | Iterable[str] | dict[str, bool | list[str]]
     ) -> AbstractContextManager[None]:

src/sentry/testutils/pytest/__init__.py

@@ -9,6 +9,7 @@
     "sentry.testutils.pytest.relay",
     "sentry.testutils.pytest.metrics",
     "sentry.testutils.pytest.stale_database_reads",
+    "sentry.testutils.pytest.savepoints",
     "sentry.testutils.pytest.transactional_flush",
     "sentry.testutils.pytest.json_report_reruns",
     "sentry.testutils.pytest.show_flaky_failures",