diff --git a/tests/laborious/activities/test_opc.py b/tests/laborious/activities/test_opc.py
index e9c9d74..c4c9051 100644
--- a/tests/laborious/activities/test_opc.py
+++ b/tests/laborious/activities/test_opc.py
@@ -299,8 +299,9 @@ async def test_manage_output_tags_success(opc):
 
 
 @mark.asyncio
-async def test_manage_output_tags_failed(opc):
-    opc.write_data = AsyncMock(side_effect=[0.1, None])
+@mark.parametrize('side_effect', [[0.1, None], [None, 0.2]])
+async def test_manage_output_tags_failed(opc, side_effect):
+    opc.write_data = AsyncMock(side_effect=side_effect)
     data = DataFrame({'prediction': [0.75], 'prediction_confidence': [0.95]})
     config = {
         'prediction_tags': {'tag1': {'data_type': 'float'}},
@@ -313,7 +314,7 @@ async def test_manage_output_tags_failed(opc):
         metadata=metadata['metadata'],
     )
     assert output_data is False
-    assert opc_metrics == {'tag1': 0.1, 'tag2': None}
+    assert opc_metrics == {'tag1': side_effect[0], 'tag2': side_effect[1]}
     opc.write_data.assert_has_calls(
         [
             call(
@@ -335,6 +336,19 @@ async def test_manage_output_tags_failed(opc):
         ]
     )
 
+@mark.asyncio
+async def test_manage_output_tags_do_nothing(opc):
+    opc.write_data = AsyncMock(return_value=0.1)
+    data = DataFrame({'prediction': [0.75], 'prediction_confidence': [0.95]})
+    config = {
+        '_invalid_key': {'tag1': {'data_type': 'float'}},
+    }
+    output_data, opc_metrics = await opc.manage_output_tags(
+        server_id='server1', config=config, data=data, metadata=metadata['metadata'],
+    )
+    assert output_data is True
+    assert opc_metrics == {}
+    opc.write_data.assert_not_called()
 
 @mark.asyncio
 @patch('laborious.activities.opc.DataFrame')