Prepared for playback engine

test/test_derive.py

@@ -1,7 +1,9 @@
+import logging
 from queue import Empty, Queue
 import time
 from uuid import UUID, uuid4
 
+import pytest
 from dynalab_core.derive import DeriveRegistry
 from dynalab_core.protocols.packets.data import ValueDescriptor
 from dynalab_core.protocols.packets.handshake import SignalDescriptor
@@ -19,6 +21,14 @@ def add(left: ValueDescriptor, right: ValueDescriptor, output: SignalDescriptor)
     )
 """
 
+FAILING_PROCESSING_FUNCTION = """
+from dynalab_core.protocols.packets.data import ValueDescriptor
+from dynalab_core.protocols.packets.handshake import SignalDescriptor
+
+def fail(value: ValueDescriptor, output: SignalDescriptor) -> ValueDescriptor:
+    raise RuntimeError("derive failed")
+"""
+
 
 def test_derive_registry_routes_with_live_values() -> None:
     output_queue: Queue[ValueDescriptor] = Queue()
@@ -32,9 +42,7 @@ def test_derive_registry_routes_with_live_values() -> None:
         unit = registry.register(
             PROCESSING_FUNCTION, [left_signal, right_signal], output_signal
         )
-        right_value = ValueDescriptor(
-            signal_id=right_signal.id, value=2.0, timestamp=1
-        )
+        right_value = ValueDescriptor(signal_id=right_signal.id, value=2.0, timestamp=1)
         live_values[right_signal.id] = right_value
         left_value = ValueDescriptor(signal_id=left_signal.id, value=3.0, timestamp=2)
 
@@ -59,6 +67,7 @@ def test_derive_registry_routes_with_live_values() -> None:
     assert result.value == 5.0
     assert result.timestamp == left_value.timestamp
 
+
 def test_derive_registry_ignores_unknown_unit_on_unregister() -> None:
     registry = DeriveRegistry(Queue(), lambda signal_id: None)
 
@@ -66,3 +75,34 @@ def test_derive_registry_ignores_unknown_unit_on_unregister() -> None:
         registry.unregister(uuid4())
     finally:
         registry.stop()
+
+
+def test_derive_worker_logs_failure_and_stops(
+    caplog: pytest.LogCaptureFixture,
+) -> None:
+    input_signal = SignalDescriptor(id=uuid4(), name="Input", type="number")
+    output_signal = SignalDescriptor(id=uuid4(), name="Output", type="number")
+    registry = DeriveRegistry(Queue(), lambda signal_id: None)
+
+    with caplog.at_level(logging.DEBUG, logger="dynalab_core"):
+        try:
+            unit = registry.register(
+                FAILING_PROCESSING_FUNCTION, [input_signal], output_signal
+            )
+            unit.put_data(
+                [ValueDescriptor(signal_id=input_signal.id, value=1.0, timestamp=1)]
+            )
+            assert unit._stopped_event.wait(1.0)
+            assert registry.get_all_signal_descriptors() == []
+        finally:
+            registry.stop()
+
+    failures = [
+        record
+        for record in caplog.records
+        if getattr(record, "event", None) == "derive.worker_failed"
+    ]
+    assert len(failures) == 1
+    assert failures[0].derive_uuid == str(unit.uuid())
+    assert failures[0].exception_type == "RuntimeError"
+    assert failures[0].exc_info is not None