From 29d371cc24900e3e458d20dac8eba5f8668faa6f Mon Sep 17 00:00:00 2001
From: David Elner <david@davidelner.com>
Date: Thu, 29 Apr 2021 15:06:30 -0400
Subject: [PATCH 1/2] Changed: Rubocop RSpec hook rule.

---
 .rubocop.yml | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/.rubocop.yml b/.rubocop.yml
index ce7d842ce4..931770f0ab 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -239,6 +239,10 @@ RSpec/LeadingSubject:
 RSpec/ImplicitSubject:
   Enabled: false
 
+# Enforces empty line after hook declaration.
+RSpec/EmptyLineAfterHook:
+  Enabled: false
+
 # Enforces empty line after subject declaration.
 RSpec/EmptyLineAfterSubject:
   Enabled: false

From 8a35b6e733cf951a3d3fb487428d4ae4d33db5f3 Mon Sep 17 00:00:00 2001
From: David Elner <david@davidelner.com>
Date: Thu, 29 Apr 2021 15:07:10 -0400
Subject: [PATCH 2/2] Fixed: ActionPack instrumentation #starts_with? error
 when running standalone.

---
 .../action_controller/instrumentation.rb      |  2 +-
 lib/ddtrace/contrib/action_pack/utils.rb      |  2 +-
 .../action_controller/instrumentation_spec.rb | 78 +++++++++++++++++++
 3 files changed, 80 insertions(+), 2 deletions(-)
 create mode 100644 spec/ddtrace/contrib/action_pack/action_controller/instrumentation_spec.rb

diff --git a/lib/ddtrace/contrib/action_pack/action_controller/instrumentation.rb b/lib/ddtrace/contrib/action_pack/action_controller/instrumentation.rb
index 06bd64159d..f1fce69c2e 100644
--- a/lib/ddtrace/contrib/action_pack/action_controller/instrumentation.rb
+++ b/lib/ddtrace/contrib/action_pack/action_controller/instrumentation.rb
@@ -61,7 +61,7 @@ def finish_processing(payload)
                 # [christian] in some cases :status is not defined,
                 # rather than firing an error, simply acknowledge we don't know it.
                 status = payload.fetch(:status, '?').to_s
-                span.status = 1 if status.starts_with?('5')
+                span.status = 1 if status.start_with?('5')
               elsif Utils.exception_is_error?(exception)
                 span.set_error(exception)
               end
diff --git a/lib/ddtrace/contrib/action_pack/utils.rb b/lib/ddtrace/contrib/action_pack/utils.rb
index 14b8a5626e..4e56a8fe53 100644
--- a/lib/ddtrace/contrib/action_pack/utils.rb
+++ b/lib/ddtrace/contrib/action_pack/utils.rb
@@ -11,7 +11,7 @@ def self.exception_is_error?(exception)
             # You can add custom errors via `config.action_dispatch.rescue_responses`
             status = ::ActionDispatch::ExceptionWrapper.status_code_for_exception(exception.class.name)
             # Only 5XX exceptions are actually errors (e.g. don't flag 404s)
-            status.to_s.starts_with?('5')
+            status.to_s.start_with?('5')
           else
             true
           end
diff --git a/spec/ddtrace/contrib/action_pack/action_controller/instrumentation_spec.rb b/spec/ddtrace/contrib/action_pack/action_controller/instrumentation_spec.rb
new file mode 100644
index 0000000000..a0ad23475f
--- /dev/null
+++ b/spec/ddtrace/contrib/action_pack/action_controller/instrumentation_spec.rb
@@ -0,0 +1,78 @@
+require 'ddtrace/contrib/support/spec_helper'
+
+require 'action_controller'
+require 'ddtrace'
+
+# TODO: We plan on rewriting much of this instrumentation to bring it up to
+#       present day patterns/conventions. For now, just test a few known cases.
+RSpec.describe Datadog::Contrib::ActionPack::ActionController::Instrumentation do
+  describe '::finish_processing' do
+    subject(:finish_processing) { described_class.finish_processing(payload) }
+
+    context 'given a payload that been started' do
+      before { described_class.start_processing(payload) }
+      after { span.finish }
+
+      let(:action_dispatch_exception) { nil }
+      let(:action_name) { 'index' }
+      let(:controller_class) { stub_const('TestController', Class.new(ActionController::Base)) }
+      let(:env) { { 'rack.url_scheme' => 'http' } }
+      let(:payload) do
+        {
+          controller: controller_class,
+          action: action_name,
+          env: env,
+          headers: {
+            # The exception this controller was given in the request,
+            # which is typical if the controller is configured to handle exceptions.
+            request_exception: action_dispatch_exception
+          },
+          tracing_context: {}
+        }
+      end
+
+      let(:span) { payload[:tracing_context][:dd_request_span] }
+
+      context 'with a 200 OK response' do
+        before do
+          expect(Datadog.logger).to_not receive(:error)
+          finish_processing
+        end
+
+        describe 'the Datadog span' do
+          it do
+            expect(span).to_not have_error
+          end
+        end
+      end
+
+      context 'with a 500 Server Error response' do
+        let(:error) do
+          begin
+            raise 'Test error'
+          rescue StandardError => e
+            e
+          end
+        end
+
+        let(:payload) do
+          super().merge(
+            exception: [error.class.name, error.message],
+            exception_object: error
+          )
+        end
+
+        before do
+          expect(Datadog.logger).to_not receive(:error)
+          finish_processing
+        end
+
+        describe 'the Datadog span' do
+          it do
+            expect(span).to have_error
+          end
+        end
+      end
+    end
+  end
+end