feat: add noop for Trace::Span attributes and events (#1881)

* fix: add two noop function for span

* add test case

---------

Co-authored-by: Kayla Reopelle <[email protected]>

Author: xuan-cao-swi

api/lib/opentelemetry/trace/span.rb

@@ -78,6 +78,18 @@ def add_attributes(attributes)
         self
       end
 
+      # Retrieve attributes
+      #
+      # Note that the OpenTelemetry project
+      # {https://github.com/open-telemetry/opentelemetry-specification/blob/master/specification/data-semantic-conventions.md
+      # documents} certain "standard attributes" that have prescribed semantic
+      # meanings.
+      #
+      # @return [hash] returns empty hash
+      def attributes
+        {}
+      end
+
       # Add a link to a {Span}.
       #
       # Adding links at span creation using the `links` option is preferred
@@ -123,6 +135,18 @@ def add_event(name, attributes: nil, timestamp: nil)
         self
       end
 
+      # Retrieve events
+      #
+      # Note that the OpenTelemetry project
+      # {https://github.com/open-telemetry/opentelemetry-specification/blob/master/specification/data-semantic-conventions.md
+      # documents} certain "standard event names and keys" which have
+      # prescribed semantic meanings.
+      #
+      # @return [array] returns empty array
+      def events
+        []
+      end
+
       # Record an exception during the execution of this span. Multiple exceptions
       # can be recorded on a span.
       #

api/test/opentelemetry/trace/span_test.rb

@@ -36,6 +36,17 @@
     end
   end
 
+  describe '#attributes' do
+    it 'returns empty hash' do
+      _(span.attributes).must_equal({})
+    end
+
+    it 'returns empty hash even after modification attempts' do
+      span.attributes['test'] = 'value'
+      _(span.attributes).must_equal({})
+    end
+  end
+
   describe '#add_link' do
     it 'returns self' do
       _(span.add_link(OpenTelemetry::Trace::Link.new(span_context))).must_equal(span)
@@ -60,6 +71,17 @@
     end
   end
 
+  describe '#events' do
+    it 'returns empty array' do
+      _(span.events).must_equal([])
+    end
+
+    it 'returns empty array even after modification attempts' do
+      span.events << 'test event'
+      _(span.events).must_equal([])
+    end
+  end
+
   describe '#record_exception' do
     it 'returns nil' do
       _(span.record_exception(StandardError.new('oops'))).must_be_nil