include sub-account assets in the right order

fixes #9674

with more than one level of sub-account branding, the branding
was being included in the wrong order for certain pages.

test plan:
- make sure global includes and sub-account includes are enabled
  on the root account
- make a sub account (S1) and enable sub-account includes
- make a sub account of that sub account (SS1)
- add custom branding on both sub accounts, where the branding on
  SS1 is meant to override the branding on S1
- the css should override in the right order

Change-Id: I7579a885e057ce06843bb0b73f2f297391466afa
Reviewed-on: https://gerrit.instructure.com/12567
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Cody Cutrer <cody@instructure.com>

app/helpers/application_helper.rb

@@ -663,7 +663,7 @@ module ApplicationHelper
     @include_accounts = [Account.site_admin, @domain_root_account]
     if @domain_root_account.try(:sub_account_includes?)
       # get the deepest account to start looking for branding
-      common_chain = account_context(@context).try(:account_chain)
+      common_chain = account_context(@context).try(:account_chain).try(:reverse)
       common_chain ||= @current_user.common_account_chain(@domain_root_account) if @current_user.present?
       @include_accounts.concat(common_chain) if common_chain.present?
     end

spec/helpers/application_helper_spec.rb

@@ -170,6 +170,7 @@ describe ApplicationHelper do
 
         @sub_account1 = account_model(:root_account => @domain_root_account)
         @sub_account1.settings = @sub_account1.settings.merge({ :global_stylesheet => '/path/to/sub1/css' })
+        @sub_account1.settings = @sub_account1.settings.merge({ :sub_account_includes => true })
         @sub_account1.save!
 
         @sub_account2 = account_model(:root_account => @domain_root_account)
@@ -230,6 +231,32 @@ describe ApplicationHelper do
         output.should have_tag 'link'
         output.scan(%r{/path/to/(sub1/|sub2/|root/|admin/)?css}).should eql [['admin/'], ['root/']]
       end
+
+      it "should include multiple levesl of sub-account css in the right order for course page" do
+        @sub_sub_account1 = account_model(:parent_account => @sub_account1, :root_account => @domain_root_account)
+        @sub_sub_account1.settings = @sub_sub_account1.settings.merge({ :global_stylesheet => '/path/to/subsub1/css' })
+        @sub_sub_account1.save!
+
+        @context = @sub_sub_account1.courses.create!
+        output = include_account_css
+        output.should have_tag 'link'
+        output.scan(%r{/path/to/(subsub1/|sub1/|sub2/|root/|admin/)?css}).should eql [['admin/'], ['root/'], ['sub1/'], ['subsub1/']]
+      end
+
+      it "should include multiple levesl of sub-account css in the right order" do
+        @sub_sub_account1 = account_model(:parent_account => @sub_account1, :root_account => @domain_root_account)
+        @sub_sub_account1.settings = @sub_sub_account1.settings.merge({ :global_stylesheet => '/path/to/subsub1/css' })
+        @sub_sub_account1.save!
+
+        @course = @sub_sub_account1.courses.create!
+        @course.offer!
+        student_in_course(:active_all => true)
+        @context = @user
+        @current_user = @user
+        output = include_account_css
+        output.should have_tag 'link'
+        output.scan(%r{/path/to/(subsub1/|sub1/|sub2/|root/|admin/)?css}).should eql [['admin/'], ['root/'], ['sub1/'], ['subsub1/']]
+      end
     end
   end