Merge pull request #29951 from georgeclaghorn/action-view-test-flow

Fix testing helpers that use Action View's capturing helpers (e.g. content_for)

actionview/lib/action_view/test_case.rb

@@ -103,6 +103,7 @@ module ActionView
       def setup_with_controller
         @controller = ActionView::TestCase::TestController.new
         @request = @controller.request
+        @view_flow = ActionView::OutputFlow.new
         # empty string ensures buffer has UTF-8 encoding as
         # new without arguments returns ASCII-8BIT encoded buffer like String#new
         @output_buffer = ActiveSupport::SafeBuffer.new ""
@@ -246,6 +247,7 @@ module ActionView
         :@test_passed,
         :@view,
         :@view_context_class,
+        :@view_flow,
         :@_subscribers,
         :@html_document
       ]

actionview/test/template/test_case_test.rb

@@ -282,6 +282,14 @@ module ActionView
       @customers = [DeveloperStruct.new("Eloy"), DeveloperStruct.new("Manfred")]
       assert_match(/Hello: EloyHello: Manfred/, render(file: "test/list"))
     end
+
+    test "is able to use helpers that depend on the view flow" do
+      assert_not content_for?(:foo)
+
+      content_for :foo, "bar"
+      assert content_for?(:foo)
+      assert_equal "bar", content_for(:foo)
+    end
   end
 
   class AssertionsTest < ActionView::TestCase