Let the instrumenter log exceptions too (#746)

Author: foca

lib/http/features/instrumentation.rb

@@ -19,11 +19,12 @@ module Features
     #    and `finish` so the duration of the request can be calculated.
     #
     class Instrumentation < Feature
-      attr_reader :instrumenter, :name
+      attr_reader :instrumenter, :name, :error_name
 
       def initialize(instrumenter: NullInstrumenter.new, namespace: "http")
         @instrumenter = instrumenter
         @name = "request.#{namespace}"
+        @error_name = "error.#{namespace}"
       end
 
       def wrap_request(request)
@@ -39,6 +40,10 @@ def wrap_response(response)
         response
       end
 
+      def on_error(request, error)
+        instrumenter.instrument(error_name, :request => request, :error => error)
+      end
+
       HTTP::Options.register_feature(:instrumentation, self)
 
       class NullInstrumenter

spec/lib/http/features/instrumentation_spec.rb

@@ -59,4 +59,23 @@ def finish(_name, payload)
       expect(instrumenter.output[:finish]).to eq(:response => response)
     end
   end
+
+  describe "logging errors" do
+    let(:request) do
+      HTTP::Request.new(
+        :verb    => :post,
+        :uri     => "https://example.com/",
+        :headers => {:accept => "application/json"},
+        :body    => '{"hello": "world!"}'
+      )
+    end
+
+    let(:error) { HTTP::TimeoutError.new }
+
+    it "should log the error" do
+      feature.on_error(request, error)
+
+      expect(instrumenter.output[:finish]).to eq(:request => request, :error => error)
+    end
+  end
 end