Fix eiger stream data publish

pyproject.toml

@@ -33,6 +33,7 @@ dev = [
     "pre-commit",
     "pydata-sphinx-theme>=0.12",
     "pytest-cov",
+    "pytest-mock",
     "pytest-mypy",
     "pytest-flake8",
     "pytest-black",

src/tickit_devices/eiger/eiger_adapters.py

@@ -430,5 +430,5 @@ def __init__(self, device: EigerDevice) -> None:
 
     def after_update(self) -> None:
         """Updates IOC values immediately following a device update."""
-        buffered_data = self.device.stream.consume_data()
-        self.add_message_to_stream([list(buffered_data)])
+        if buffered_data := list(self.device.stream.consume_data()):
+            self.add_message_to_stream(buffered_data)

tests/eiger/test_eiger_adapters.py

@@ -0,0 +1,21 @@
+from pytest_mock import MockerFixture
+
+from tickit_devices.eiger.eiger_adapters import EigerZMQAdapter
+
+
+def test_after_update(mocker: MockerFixture) -> None:
+    test_data = [b"data", b"some more data"]
+
+    # Mock consume_data to return with data the first time and nothing the second time
+    device_mock = mocker.MagicMock()
+    device_mock.stream.consume_data.side_effect = [test_data, []]
+
+    zmq_adapter = EigerZMQAdapter(device_mock)
+    add_mock = mocker.patch.object(zmq_adapter, "add_message_to_stream")
+
+    # Test after_update only calls add_message_to_stream with non-empty data
+    zmq_adapter.after_update()
+    add_mock.assert_called_once_with(test_data)
+    add_mock.reset_mock()
+    zmq_adapter.after_update()
+    add_mock.assert_not_called()