feat: add example.id attribute to RSpec spans

Record RSpec's example.id as a span attribute to provide unique identification for each test example. This is particularly valuable when examples are created dynamically (e.g., within loops), where multiple examples share the same file location but have distinct IDs.

Author: americodls

instrumentation/rspec/lib/opentelemetry/instrumentation/rspec/formatter.rb

@@ -58,6 +58,7 @@ def example_group_finished(notification)
         def example_started(notification)
           example = notification.example
           attributes = {
+            'rspec.example.id' => example.id.to_s,
             'rspec.example.location' => example.location.to_s,
             'rspec.example.full_description' => example.full_description.to_s,
             'rspec.example.described_class' => example.metadata[:described_class].to_s

instrumentation/rspec/test/opentelemetry/instrumentation/rspec/formatter_test.rb

@@ -131,6 +131,10 @@ def run_example(...)
         _(subject.attributes['rspec.example.location']).must_match %r{\./test/opentelemetry/instrumentation/rspec/formatter_test.rb:\d+}
       end
 
+      it 'has an id attribute' do
+        _(subject.attributes['rspec.example.id']).must_match %r{\./test/opentelemetry/instrumentation/rspec/formatter_test.rb\[\d+:\d+\]}
+      end
+
       it 'records when the example passes' do
         _(subject.attributes['rspec.example.result']).must_equal 'passed'
       end
@@ -326,6 +330,32 @@ def run_example(...)
         _(subject.events[1].attributes['exception.message']).must_equal 'another-error'
       end
     end
+
+    describe 'dynamic examples with same location' do
+      it 'have unique example.id attributes' do
+        spans = run_rspec_with_tracing do
+          RSpec.describe('dynamic examples') do
+            [1, 2, 3].each do |num|
+              example("example #{num}") { expect(num).to be_positive }
+            end
+          end
+        end
+
+        example_spans = spans.select { |span| span.name.start_with?('example ') }
+        _(example_spans.size).must_equal 3
+
+        # All examples have the same location (same line in the loop)
+        locations = example_spans.map { |span| span.attributes['rspec.example.location'] }
+        _(locations.uniq.size).must_equal 1
+
+        # But each has a unique id
+        ids = example_spans.map { |span| span.attributes['rspec.example.id'] }
+        _(ids.uniq.size).must_equal 3
+        ids.each do |id|
+          _(id).must_match %r{\./test/opentelemetry/instrumentation/rspec/formatter_test.rb\[\d+:\d+\]}
+        end
+      end
+    end
   end
 
   describe 'using a custom tracer provider' do