emit warnings in logs when invalid spans are being skipped in tests

lib/datadog/ci/test_visibility/serializers/base.rb

@@ -162,6 +162,10 @@ def time_nano(time)
           def duration_nano(duration)
             (duration * 1e9).to_i
           end
+
+          def to_s
+            "#{self.class.name}(id:#{span_id},name:#{name})"
+          end
         end
       end
     end

lib/datadog/ci/test_visibility/transport.rb

@@ -102,7 +102,7 @@ def encode_span(trace, span)
 
             encoded
           else
-            Datadog.logger.debug { "Invalid span skipped: #{span}" }
+            Datadog.logger.warn("Invalid event skipped: #{serializer}")
             nil
           end
         end

spec/datadog/ci/test_visibility/transport_spec.rb

@@ -14,6 +14,10 @@
     )
   end
 
+  before do
+    allow(Datadog.logger).to receive(:warn)
+  end
+
   let(:dd_env) { nil }
   let(:serializers_factory) { Datadog::CI::TestVisibility::Serializers::Factories::TestLevel }
   let(:max_payload_size) { 4 * 1024 * 1024 }
@@ -84,9 +88,9 @@
 
       context "when some spans are broken" do
         let(:expected_events_count) { 3 }
+        let(:http_span) { spans.find { |span| span.type == "http" } }
 
         before do
-          http_span = spans.find { |span| span.type == "http" }
           http_span.start_time = Time.at(0)
         end
 
@@ -103,6 +107,14 @@
             expect(span_events.count).to eq(1)
           end
         end
+
+        it "logs warning that events were filtered out" do
+          subject.send_traces(traces)
+
+          expect(Datadog.logger).to have_received(:warn).with(
+            "Invalid event skipped: Datadog::CI::TestVisibility::Serializers::Span(id:#{http_span.id},name:#{http_span.name})"
+          )
+        end
       end
 
       context "when chunking is used" do