Fix finding templates for digesting for */* requests that render a non-default (html) template

actionview/lib/action_view/digestor.rb

@@ -38,10 +38,13 @@ module ActionView
       # Create a dependency tree for template named +name+.
       def tree(name, finder, partial = false, seen = {})
         logical_name = name.gsub(%r|/_|, "/")
-        formats = [finder.rendered_format]
 
-        if finder.disable_cache { finder.exists?(logical_name, [], partial, [], formats: formats) }
-          template = finder.disable_cache { finder.find(logical_name, [], partial, [], formats: formats) }
+        options = {}
+        options[:formats] = [finder.rendered_format] if finder.rendered_format
+
+        if finder.disable_cache { finder.exists?(logical_name, [], partial, [], options) }
+          template = finder.disable_cache { finder.find(logical_name, [], partial, [], options) }
+          finder.rendered_format ||= template.formats.first
 
           if node = seen[template.identifier] # handle cycles in the tree
             node

actionview/test/fixtures/digestor/api/comments/_comments.json.erb

@@ -0,0 +1 @@
+<%= render partial: "comments/comment", collection: commentable.comments %>

actionview/test/fixtures/digestor/messages/thread.json.erb

@@ -0,0 +1 @@
+<%= render "comments/comments" %>

actionview/test/template/digestor_test.rb

@@ -22,6 +22,12 @@ class FixtureFinder < ActionView::LookupContext
   end
 end
 
+class ActionView::Digestor::Node
+  def flatten
+    [self] + children.flat_map(&:flatten)
+  end
+end
+
 class TemplateDigestorTest < ActionView::TestCase
   def setup
     @cwd     = Dir.pwd
@@ -148,6 +154,17 @@ class TemplateDigestorTest < ActionView::TestCase
     assert_equal nested_deps, nested_dependencies("messages/show")
   end
 
+  def test_nested_template_deps_with_non_default_rendered_format
+    finder.rendered_format = nil
+    nested_deps = [{"comments/comments"=>["comments/comment"]}]
+    assert_equal nested_deps, nested_dependencies("messages/thread")
+  end
+
+  def test_template_formats_of_nested_deps_with_non_default_rendered_format
+    finder.rendered_format = nil
+    assert_equal [:json, :json, :json], tree_template_formats("messages/thread")
+  end
+
   def test_recursion_in_renders
     assert digest("level/recursion") # assert recursion is possible
     assert_not_nil digest("level/recursion") # assert digest is stored
@@ -334,6 +351,11 @@ class TemplateDigestorTest < ActionView::TestCase
       tree.children.map(&:to_dep_map)
     end
 
+    def tree_template_formats(template_name)
+      tree = ActionView::Digestor.tree(template_name, finder)
+      tree.flatten.map(&:template).flat_map(&:formats)
+    end
+
     def disable_resolver_caching
       old_caching, ActionView::Resolver.caching = ActionView::Resolver.caching, false
       yield