Update Action View instrumentation (#487)

gems/instruments.gemfile

@@ -4,3 +4,5 @@ gem 'httpclient'
 gem 'http'
 gem 'redis'
 gem 'moped'
+gem 'actionpack'
+gem 'actionview'

lib/scout_apm/instruments/action_view.rb

@@ -72,9 +72,67 @@ def install_using_prepend
 
         logger.info "Instrumenting ActionView::TemplateRenderer"
         ::ActionView::TemplateRenderer.prepend(ActionViewTemplateRendererInstruments)
+
+        if defined?(::ActionView::CollectionRenderer)
+          logger.info "Instrumenting ActionView::CollectionRenderer"
+          ::ActionView::CollectionRenderer.prepend(ActionViewCollectionRendererInstruments)
+        end
+      end
+
+      # In Rails 6.1 collection was moved to CollectionRenderer.
+      module ActionViewCollectionRendererInstruments
+        def render_collection(*args, **kwargs)
+          req = ScoutApm::RequestManager.lookup
+
+          maybe_template = args[3]
+
+          template_name ||= maybe_template.virtual_path rescue nil
+          template_name ||= "Unknown Collection"
+          layer_name = template_name + "/Rendering"
+
+          layer = ScoutApm::Layer.new("View", layer_name)
+          layer.subscopable!
+
+          begin
+            req.start_layer(layer)
+            if ScoutApm::Agent.instance.context.environment.supports_kwarg_delegation?
+              super(*args, **kwargs)
+            else
+              super(*args)
+            end
+          ensure
+            req.stop_layer
+          end
+        end
       end
 
       module ActionViewPartialRendererInstruments
+        # In Rails 6.1, render_partial was renamed to render_partial_template
+        def render_partial_template(*args, **kwargs)
+          req = ScoutApm::RequestManager.lookup
+
+          # Template was moved to the third argument in Rails 6.1.
+          maybe_template = args[2]
+
+          template_name ||= maybe_template.virtual_path rescue nil
+          template_name ||= "Unknown Partial"
+
+          layer_name = template_name + "/Rendering"
+          layer = ScoutApm::Layer.new("View", layer_name)
+          layer.subscopable!
+
+          begin
+            req.start_layer(layer)
+            if ScoutApm::Agent.instance.context.environment.supports_kwarg_delegation?
+              super(*args, **kwargs)
+            else
+              super(*args)
+            end
+          ensure
+            req.stop_layer
+          end
+        end
+
         # In Rails 6, the signature changed to pass the view & template args directly, as opposed to through the instance var
         # New signature is: def render_partial(view, template)
         def render_partial(*args, **kwargs)
@@ -83,7 +141,7 @@ def render_partial(*args, **kwargs)
           maybe_template = args[1]
 
           template_name = @template.virtual_path rescue nil        # Works on Rails 3.2 -> end of Rails 5 series
-          template_name ||= maybe_template.virtual_path rescue nil # Works on Rails 6 -> 6.0.3.5
+          template_name ||= maybe_template.virtual_path rescue nil # Works on Rails 6 -> 6.0.6
           template_name ||= "Unknown Partial"
 
           layer_name = template_name + "/Rendering"
@@ -102,13 +160,14 @@ def render_partial(*args, **kwargs)
           end
         end
 
+        # This method was moved in Rails 6.1 to CollectionRender. 
         def collection_with_template(*args, **kwargs)
           req = ScoutApm::RequestManager.lookup
 
           maybe_template = args[1]
 
           template_name = @template.virtual_path rescue nil # Works on Rails 3.2 -> end of Rails 5 series
-          template_name ||= maybe_template.virtual_path rescue nil # Works on Rails 6 -> 6.0.3.5
+          template_name ||= maybe_template.virtual_path rescue nil # Works on Rails 6 -> 6.0.6
           template_name ||= "Unknown Collection"
           layer_name = template_name + "/Rendering"
 
@@ -137,7 +196,7 @@ def render_template(*args)
           maybe_template = args[1]
 
           template_name = args[0].virtual_path rescue nil # Works on Rails 3.2 -> end of Rails 5 series
-          template_name ||= maybe_template.virtual_path rescue nil # Works on Rails 6 -> 6.1.3
+          template_name ||= maybe_template.virtual_path rescue nil # Works on Rails 6 -> 7.1.3
           template_name ||= "Unknown"
           layer_name = template_name + "/Rendering"
 

test/test_helper.rb

@@ -65,7 +65,13 @@ def method_missing(sym)
   end
 end
 
+def remove_rails_namespace
+  Object.send(:remove_const, "Rails") if defined?(Rails)
+end
+
 def fake_rails(version)
+  remove_rails_namespace if (ENV["SCOUT_TEST_FEATURES"] || "").include?("instruments")
+
   Kernel.const_set("Rails", Module.new)
   Kernel.const_set("ActionController", Module.new)
   r = Kernel.const_get("Rails")

test/unit/instruments/action_view_test.rb

@@ -0,0 +1,102 @@
+# Most of this was taken from Rails:
+# https://github.com/rails/rails/blob/v7.1.3/actionview/test/actionpack/controller/render_test.rb
+# https://github.com/rails/rails/blob/v7.1.3/actionview/test/abstract_unit.rb
+
+if (ENV["SCOUT_TEST_FEATURES"] || "").include?("instruments")
+  require 'test_helper'
+  require 'action_view'
+  require 'action_pack'
+  require 'action_controller'
+
+  FIXTURE_LOAD_PATH = File.expand_path("fixtures", __dir__)
+
+  include ActionView::Context
+  include ActionView::Helpers::TagHelper
+  include ActionView::Helpers::TextHelper
+
+  module ActionController
+
+    class Base
+      self.view_paths = FIXTURE_LOAD_PATH
+
+      def self.test_routes(&block)
+        routes = ActionDispatch::Routing::RouteSet.new
+        routes.draw(&block)
+        include routes.url_helpers
+        routes
+      end
+    end
+
+    class TestCase
+      include ActionDispatch::TestProcess
+
+      def self.with_routes(&block)
+        routes = ActionDispatch::Routing::RouteSet.new
+        routes.draw(&block)
+        include Module.new {
+          define_method(:setup) do
+            super()
+            @routes = routes
+            @controller.singleton_class.include @routes.url_helpers if @controller
+          end
+        }
+        routes
+      end
+    end
+  end
+
+  class TestController < ActionController::Base
+
+    def render_test_view
+      render template: "test_view"
+    end
+  end
+
+  class RenderTest < ActionController::TestCase
+
+    tests TestController
+
+    with_routes do
+      get :render_test_view, to: "test#render_test_view"
+    end
+
+    def setup
+      super
+      @controller.logger      = ActiveSupport::Logger.new(nil)
+      ActionView::Base.logger = ActiveSupport::Logger.new(nil)
+
+      @request.host = "www.scoutapm.com"
+
+      @old_view_paths = ActionController::Base.view_paths
+      ActionController::Base.view_paths = FIXTURE_LOAD_PATH
+    end
+
+    def teardown
+      ActionView::Base.logger = nil
+
+      ActionController::Base.view_paths = @old_view_paths
+    end
+
+    def test_partial_instrumentation
+      recorder = FakeRecorder.new
+      agent_context.recorder = recorder
+
+      instrument = ScoutApm::Instruments::ActionView.new(agent_context)
+      instrument.install(prepend: true)
+
+      get :render_test_view
+      assert_response :success
+
+      root_layer = recorder.requests.first.root_layer
+      children = root_layer.children.to_a
+      assert_equal 2, children.size
+
+      partial_layer = children[0]
+      collection_layer = children[1]
+
+      assert_equal "test_view/Rendering", root_layer.name
+      assert_equal "test/_test_partial/Rendering", partial_layer.name
+      assert_equal "test/_test_partial_collection/Rendering", collection_layer.name
+    end
+  end
+end

test/unit/instruments/fixtures/test/_test_partial.html.erb

@@ -0,0 +1,3 @@
+<div>
+  <p><%= message %></p>
+</div>

test/unit/instruments/fixtures/test/_test_partial_collection.html.erb

@@ -0,0 +1,3 @@
+<div>
+  <p><%= index %></p>
+</div>

test/unit/instruments/fixtures/test_view.html.erb

@@ -0,0 +1,10 @@
+<html>
+  <head>
+    <title>View</title>
+  </head>
+  <body>
+    <h1>View</h1>
+    <%= render partial: "test_partial", locals: { message: 'Partial' } %>
+    <%= render partial: "test_partial_collection", collection: [1, 2, 3], as: :index %>
+  </body>
+</html>