fix!: total order constraint on span.status=

sdk/lib/opentelemetry/sdk/trace/span.rb

@@ -167,20 +167,23 @@ def record_exception(exception, attributes: nil)
 
         # Sets the Status to the Span
         #
-        # If used, this will override the default Span status. Default is OK.
+        # If used, this will override the default Span status. Default has code = Status::UNSET.
         #
-        # Only the value of the last call will be recorded, and implementations
-        # are free to ignore previous calls.
+        # An attempt to set the status with code == Status::UNSET is ignored.
+        # If the status is set with code == Status::OK, any further attempt to set the status
+        # is ignored.
         #
         # @param [Status] status The new status, which overrides the default Span
-        #   status, which is OK.
+        #   status, which has code = Status::UNSET.
         #
         # @return [void]
         def status=(status)
+          return if status.code == OpenTelemetry::Trace::Status::UNSET
+
           @mutex.synchronize do
             if @ended
               OpenTelemetry.logger.warn('Calling status= on an ended Span.')
-            else
+            elsif @status.code != OpenTelemetry::Trace::Status::OK
               @status = status
             end
           end

sdk/test/opentelemetry/sdk/trace/span_test.rb

@@ -324,15 +324,37 @@
 
   describe '#status=' do
     it 'sets the status' do
-      span.status = Status.new(1, description: 'cancelled')
+      span.status = Status.new(Status::ERROR, description: 'cancelled')
       _(span.status.description).must_equal('cancelled')
+      _(span.status.code).must_equal(Status::ERROR)
     end
 
     it 'does not set the status if span is ended' do
       span.finish
       span.status = Status.new(Status::ERROR, description: 'cancelled')
       _(span.status.code).must_equal(Status::UNSET)
     end
+
+    it 'does not set the status if asked to set to UNSET' do
+      span.status = Status.new(Status::ERROR, description: 'cancelled')
+      span.status = Status.new(Status::UNSET, description: 'actually, maybe it is OK?')
+      _(span.status.description).must_equal('cancelled')
+      _(span.status.code).must_equal(Status::ERROR)
+    end
+
+    it 'does not override the status once set to OK' do
+      span.status = Status.new(Status::OK, description: 'nothing to see here')
+      span.status = Status.new(Status::ERROR, description: 'cancelled')
+      _(span.status.description).must_equal('nothing to see here')
+      _(span.status.code).must_equal(Status::OK)
+    end
+
+    it 'allows overriding ERROR with OK' do
+      span.status = Status.new(Status::ERROR, description: 'cancelled')
+      span.status = Status.new(Status::OK, description: 'nothing to see here')
+      _(span.status.description).must_equal('nothing to see here')
+      _(span.status.code).must_equal(Status::OK)
+    end
   end
 
   describe '#name=' do