trace data-partition-id even in None case

app/middleware/traces_middleware.py

@@ -91,8 +91,6 @@ class TracingMiddleware(BaseHTTPMiddleware):
         ctx_partition_id = get_or_create_ctx().partition_id
         partition_id = ctx_partition_id if ctx_partition_id is not None \
             else request.headers.get(conf.PARTITION_ID_HEADER_NAME)
-        # only put in the trace if there is data    
-        if partition_id is not None:
         tracer.add_attribute_to_current_span(
             attribute_key=conf.PARTITION_ID_HEADER_NAME,
             attribute_value=partition_id)

tests/unit/middleware/traces_middleware_test.py

@@ -88,10 +88,11 @@ def test_about_call_traces_existing_data_partition_id(client: TestClient):
     response = client.get(build_url("/about"))
     assert response.status_code == 200
     
-    # one call was exported, without data-partition-id
+    # one call was exported, with data-partition-id
     assert len(wdms_app.trace_exporter.exported) == 1  # one call => one export
     spandata = wdms_app.trace_exporter.exported[0]
-    assert 'data-partition-id' not in spandata.attributes.keys()
+    assert 'data-partition-id' in spandata.attributes.keys()
+    assert spandata.attributes['data-partition-id'] is None
 
     # data-partition-id header -> works as well
     client.get(build_url("/about"), headers={'data-partition-id': 'some partition id'})