Fix that render layout should also be picked up by the template dependency tracker, but only half-ways. You can add that layout option on the same render call, and both templates should be added to the dependency tree. But thats going to require a more serious rework of the tracker. Please do help fix this part of it too. For now, render layout needs to be on its own line.

3 files changed, 29 insertions, 4 deletions

diff --git a/actionview/CHANGELOG.md b/actionview/CHANGELOG.md
index f4a12360d7..3fc2ab178c 100644
--- a/actionview/CHANGELOG.md
+++ b/actionview/CHANGELOG.md
@@ -1,3 +1,7 @@
+*   Fix that render layout: 'messages/layout' should also be added to the dependency tracker tree.
+
+    *DHH*
+
 *   Add `PartialIteration` object used when rendering collections.
 
     The iteration object is available as the local variable
diff --git a/actionview/lib/action_view/dependency_tracker.rb b/actionview/lib/action_view/dependency_tracker.rb
index 0ccf2515c5..e34bdd4a46 100644
--- a/actionview/lib/action_view/dependency_tracker.rb
+++ b/actionview/lib/action_view/dependency_tracker.rb
@@ -53,6 +53,12 @@ module ActionView
         \s*                          # followed by optional spaces
       /x
 
+      # Part of any hash containing the :layout key
+      LAYOUT_HASH_KEY = /
+        (?:\blayout:|:layout\s*=>)   # layout key in either old or new style hash syntax
+        \s*                          # followed by optional spaces
+      /x
+
       # Matches:
       #   partial: "comments/comment", collection: @all_comments => "comments/comment"
       #   (object: @single_comment, partial: "comments/comment") => "comments/comment"
@@ -65,9 +71,9 @@ module ActionView
       #    topics          => "topics/topic"
       #   (message.topics) => "topics/topic"
       RENDER_ARGUMENTS = /\A
-        (?:\s*\(?\s*)                             # optional opening paren surrounded by spaces
-        (?:.*?#{PARTIAL_HASH_KEY})?               # optional hash, up to the partial key declaration
-        (?:#{STRING}|#{VARIABLE_OR_METHOD_CHAIN}) # finally, the dependency name of interest
+        (?:\s*\(?\s*)                                  # optional opening paren surrounded by spaces
+        (?:.*?#{PARTIAL_HASH_KEY}|#{LAYOUT_HASH_KEY})? # optional hash, up to the partial or layout key declaration
+        (?:#{STRING}|#{VARIABLE_OR_METHOD_CHAIN})      # finally, the dependency name of interest
       /xm
 
       def self.call(name, template)
@@ -85,8 +91,8 @@ module ActionView
       attr_reader :name, :template
       private :name, :template
 
-      private
 
+      private
         def source
           template.source
         end
diff --git a/actionview/test/template/dependency_tracker_test.rb b/actionview/test/template/dependency_tracker_test.rb
index 6c780f2297..bb375076c6 100644
--- a/actionview/test/template/dependency_tracker_test.rb
+++ b/actionview/test/template/dependency_tracker_test.rb
@@ -60,6 +60,21 @@ class ERBTrackerTest < Minitest::Test
     assert_equal ["messages/message123"], tracker.dependencies
   end
 
+  def test_dependency_of_template_partial_with_layout
+    skip # FIXME: Needs to be fixed properly, right now we can only match one dependency per line. Need multiple!
+    template = FakeTemplate.new("<%# render partial: 'messages/show', layout: 'messages/layout' %>", :erb)
+    tracker = make_tracker("multiple/_dependencies", template)
+
+    assert_equal ["messages/layout", "messages/show"], tracker.dependencies
+  end
+
+  def test_dependency_of_template_layout_standalone
+    template = FakeTemplate.new("<%# render layout: 'messages/layout' do %>", :erb)
+    tracker = make_tracker("messages/layout", template)
+
+    assert_equal ["messages/layout"], tracker.dependencies
+  end
+
   def test_finds_dependency_in_correct_directory
     template = FakeTemplate.new("<%# render(message.topic) %>", :erb)
     tracker = make_tracker("messages/_message", template)