Fix: Runner adds exceptions to instrumentation payload

lib/racecar/runner.rb

@@ -201,6 +201,7 @@ def process(message)
             consumer.store_offset(message)
           end
         rescue => e
+          instrumentation_payload[:exception] = e
           instrumentation_payload[:unrecoverable_delivery_error] = reset_producer_on_unrecoverable_delivery_errors(e)
           instrumentation_payload[:retries_count] = pause.pauses_count
           config.error_handler.call(e, instrumentation_payload)
@@ -232,6 +233,7 @@ def process_batch(messages)
             processor.deliver!
             consumer.store_offset(messages.last)
           rescue => e
+            instrumentation_payload[:exception] = e
             instrumentation_payload[:unrecoverable_delivery_error] = reset_producer_on_unrecoverable_delivery_errors(e)
             instrumentation_payload[:retries_count] = pause.pauses_count
             config.error_handler.call(e, instrumentation_payload)

spec/runner_spec.rb

@@ -246,8 +246,14 @@ def consumer_rebalance_listener=(_listenr)
 end
 
 class FakeInstrumenter < Racecar::Instrumenter
-  def initialize(*)
+  def initialize(received = [])
     super(backend: Racecar::NullInstrumenter)
+    @received = received
+  end
+
+  def instrument(event_name, payload = {}, &block)
+    @received << [event_name, payload]
+    super
   end
 end
 
@@ -375,7 +381,8 @@ def initialize(*)
   let(:config) { Racecar::Config.new }
   let(:logger) { Logger.new(StringIO.new) }
   let(:kafka)  { FakeRdkafka.new(runner: runner) }
-  let(:instrumenter) { FakeInstrumenter.new }
+  let(:instrumenter) { FakeInstrumenter.new(instrumented_events) }
+  let(:instrumented_events) { [] }
 
   let(:runner) do
     Racecar::Runner.new(processor, config: config, logger: logger, instrumenter: instrumenter)
@@ -419,8 +426,9 @@ def initialize(*)
         create_time: nil,
         key: nil,
         value: error,
+        exception: error,
         headers: nil,
-        retries_count: anything,
+        retries_count: instance_of(Integer),
         unrecoverable_delivery_error: false,
       }
 
@@ -431,6 +439,18 @@ def initialize(*)
       runner.run
     end
 
+    it "adds the exception to the instrumentation payload" do
+      error = StandardError.new("surprise")
+
+      kafka.deliver_message(error, topic: "greetings")
+
+      runner.run
+
+      expect(instrumented_events).to include(
+        ["process_message", hash_including(exception: error) ]
+      )
+    end
+
     it "keeps track of the number of retries when a message causes an exception" do
       error = StandardError.new("surprise")
 
@@ -555,6 +575,7 @@ def initialize(*)
         message_count: 1,
         retries_count: anything,
         unrecoverable_delivery_error: false,
+        exception: error,
       }
 
       expect(config.error_handler).to receive(:call).at_least(:once).with(error, info)