Tests clear flow tombstones between modules with the other engine rows, and the tombstone test commits its prune before checking the count, so a wrong count no longer holds the write lock over the tests after it

backend/tests/conftest.py

@@ -18,6 +18,7 @@ from fluksio.main import app
 from fluksio.models import (
     EngineEvent,
     FlowRun,
+    FlowTombstone,
     MetricBucket,
     Run,
     RunArtifact,
@@ -69,7 +70,8 @@ def db() -> Generator[Session, None, None]:
 
 
 #: Tables the engine writes to on its own, from the collector and the run
-#: service the module-scoped app starts.
+#: service the module-scoped app starts, and the tombstones a flow deleted
+#: through it leaves for that history.
 _ENGINE_TABLES = (
     RunArtifact,
     RunMetric,
@@ -78,6 +80,7 @@ _ENGINE_TABLES = (
     FlowRun,
     EngineEvent,
     MetricBucket,
+    FlowTombstone,
 )
 
 

backend/tests/test_tombstones.py

@@ -36,8 +36,11 @@ def test_a_tombstone_stays_while_history_names_its_id(db: Session) -> None:
     assert graves.recorded("wren_train") == "wren_train"  # history, no tombstone
     assert graves.recorded("f_nothing") is None
 
-    assert tombstones.prune(db) == 1
+    # Committed before it is checked, so a wrong count does not leave this
+    # session holding the write lock for every test after it.
+    pruned = tombstones.prune(db)
     db.commit()
+    assert pruned == 1
     kept = {stone.id for stone in db.exec(select(FlowTombstone))}
     assert kept == {"f_gonegone", "f_trainee", "f_measured"}
 
@@ -45,8 +48,9 @@ def test_a_tombstone_stays_while_history_names_its_id(db: Session) -> None:
     db.exec(delete(MetricBucket))  # type: ignore[call-overload]
     db.exec(delete(EngineEvent))  # type: ignore[call-overload]
     db.commit()
-    assert tombstones.prune(db) == 3
+    pruned = tombstones.prune(db)
     db.commit()
+    assert pruned == 3
 
 
 def test_a_name_comes_from_the_live_flow_then_its_tombstone_then_the_id(