fix test coverage for DumpSeriesSink

tests/test_multi_sink.py

@@ -3,6 +3,7 @@ import pytest
 from sgn.apps import Pipeline
 
 from sgnts.sources import FakeSeriesSource
+from sgnts.sinks import DumpSeriesSink
 from sgnts.sinks import NullSeriesSink
 
 
@@ -90,5 +91,12 @@ def test_invalid_fake_series():
         pipeline.run()
 
 
+def test_invalid_dump_series_pads():
+    with pytest.raises(ValueError):
+        DumpSeriesSink(
+            sink_pad_names=("H1", "L1"),
+        )
+
+
 if __name__ == "__main__":
     test_multi_sink(None)