From f047f57530f186a4047600fd7c3a5943f86d87e5 Mon Sep 17 00:00:00 2001
From: Cliff Pruitt <cliff.pruitt@cliffpruitt.com>
Date: Fri, 15 Mar 2019 11:43:39 -0400
Subject: [PATCH] Allow assert_template(file:) to work using Rails 6

An `ActionView::Template`'s `virtual_path` is deprecated under Rails 6. This commit:

https://github.com/rails/rails/commit/9a343d148b96874a231b87906c9d6499b5e0b64a#diff-40f2a5bcf9edfd65a8efe42a05c53736L437

causes the virtual path for templates rendered using `file:` to no longer have their `virtual_path` explicitly set to nil. `rails-controller-testing` uses the absence of the `virtual_path` attribute to indicate that the template was rendered as using `file:`. See:

https://github.com/rails/rails-controller-testing/blob/master/lib/rails/controller/testing/template_assertions.rb#L34

Because the attribute is never nil with Rails 6, the ability to test something like `assert_template(file: "#{Rails.root}/public/404.html")` is broken.

This commit changes the way rendered `file:` templates are tracked. Instead of paying attention calls to `ActionView::Template#render` ( subscribing to`"!render_template.action_view"`) this update instead focuses on `ActionView::TemplateRenderer#determine_template`. Because `determine_tempalte` is not already instrumented, we need to provide our own instrumentation by redefining the method, adding instrumentation, and then handing off to `super`.
---
 lib/rails/controller/testing.rb                  |  4 ++++
 .../controller/testing/template_assertions.rb    | 16 ++++++++++------
 .../testing/template_instrumentation.rb          | 16 ++++++++++++++++
 3 files changed, 30 insertions(+), 6 deletions(-)
 create mode 100644 lib/rails/controller/testing/template_instrumentation.rb

diff --git a/lib/rails/controller/testing.rb b/lib/rails/controller/testing.rb
index 45a2b27..7b2d0fc 100644
--- a/lib/rails/controller/testing.rb
+++ b/lib/rails/controller/testing.rb
@@ -2,6 +2,7 @@
 require 'rails/controller/testing/test_process'
 require 'rails/controller/testing/integration'
 require 'rails/controller/testing/template_assertions'
+require 'rails/controller/testing/template_instrumentation'
 
 module Rails
   module Controller
@@ -10,16 +11,19 @@ def self.install
         ActiveSupport.on_load(:action_controller_test_case) do
           include Rails::Controller::Testing::TestProcess
           include Rails::Controller::Testing::TemplateAssertions
+          ActionView::TemplateRenderer.prepend(InstrumentDetermineTemplate)
         end
 
         ActiveSupport.on_load(:action_dispatch_integration_test) do
           include Rails::Controller::Testing::TemplateAssertions
           include Rails::Controller::Testing::Integration
           include Rails::Controller::Testing::TestProcess
+          ActionView::TemplateRenderer.prepend(InstrumentDetermineTemplate)
         end
 
         ActiveSupport.on_load(:action_view_test_case) do
           include Rails::Controller::Testing::TemplateAssertions
+          ActionView::TemplateRenderer.prepend(InstrumentDetermineTemplate)
         end
       end
     end
diff --git a/lib/rails/controller/testing/template_assertions.rb b/lib/rails/controller/testing/template_assertions.rb
index ad5e8ad..dcf8b1f 100644
--- a/lib/rails/controller/testing/template_assertions.rb
+++ b/lib/rails/controller/testing/template_assertions.rb
@@ -30,6 +30,16 @@ def setup_subscriptions
             end
           end
 
+          @_subscribers << ActiveSupport::Notifications.subscribe("determine_template.rails_controller_testing") do |_name, _start, _finish, _id, payload|
+            if payload[:options][:file]
+              path = payload[:template_identifier]
+              if path
+                @_files[path] += 1
+                @_files[path.split("/").last] += 1
+              end
+            end
+          end
+
           @_subscribers << ActiveSupport::Notifications.subscribe("!render_template.action_view") do |_name, _start, _finish, _id, payload|
             if virtual_path = payload[:virtual_path]
               partial = virtual_path =~ /^.*\/_[^\/]*$/
@@ -40,12 +50,6 @@ def setup_subscriptions
               end
 
               @_templates[virtual_path] += 1
-            else
-              path = payload[:identifier]
-              if path
-                @_files[path] += 1
-                @_files[path.split("/").last] += 1
-              end
             end
           end
         end
diff --git a/lib/rails/controller/testing/template_instrumentation.rb b/lib/rails/controller/testing/template_instrumentation.rb
new file mode 100644
index 0000000..08cdc27
--- /dev/null
+++ b/lib/rails/controller/testing/template_instrumentation.rb
@@ -0,0 +1,16 @@
+module Rails
+  module Controller
+    module Testing
+      module InstrumentDetermineTemplate
+        def determine_template(options)
+          super.tap do |found|
+            if found
+              instrument_payload = { template_identifier: found.identifier, virtual_path: found.virtual_path, options: options }
+              ActiveSupport::Notifications.instrument("determine_template.rails_controller_testing", instrument_payload)
+            end
+          end
+        end
+      end
+    end
+  end
+end
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