Inheritance

lib/wicked_pdf/pdf_helper.rb

@@ -19,27 +19,28 @@ def self.prepended(base)
 
       base.class_eval do
         after_action :clean_temp_files
+      end
+    end
 
-        alias_method :render_without_wicked_pdf, :render
-        alias_method :render_to_string_without_wicked_pdf, :render_to_string
-
-        def render(options = nil, *args, &block)
-          render_with_wicked_pdf(options, *args, &block)
-        end
+    def render(options = nil, *args, &block)
+      render_with_wicked_pdf(options, *args, &block)
+    end
 
-        def render_to_string(options = nil, *args, &block)
-          render_to_string_with_wicked_pdf(options, *args, &block)
-        end
-      end
+    def render_to_string(options = nil, *args, &block)
+      render_to_string_with_wicked_pdf(options, *args, &block)
     end
 
     def render_with_wicked_pdf(options = nil, *args, &block)
       if options.is_a?(Hash) && options.key?(:pdf)
         log_pdf_creation
         options[:basic_auth] = set_basic_auth(options)
         make_and_send_pdf(options.delete(:pdf), (WickedPdf.config || {}).merge(options))
-      else
+      elsif respond_to?(:render_without_wicked_pdf)
+        # support alias_method_chain (module included)
         render_without_wicked_pdf(options, *args, &block)
+      else
+        # support inheritance (module prepended)
+        method(:render).super_method.call(options, *args, &block)
       end
     end
 
@@ -49,8 +50,12 @@ def render_to_string_with_wicked_pdf(options = nil, *args, &block)
         options[:basic_auth] = set_basic_auth(options)
         options.delete :pdf
         make_pdf((WickedPdf.config || {}).merge(options))
-      else
+      elsif respond_to?(:render_to_string_without_wicked_pdf)
+        # support alias_method_chain (module included)
         render_to_string_without_wicked_pdf(options, *args, &block)
+      else
+        # support inheritance (module prepended)
+        method(:render_to_string).super_method.call(options, *args, &block)
       end
     end
 

test/functional/pdf_helper_test.rb

@@ -8,7 +8,29 @@ def render_to_string(opts = {})
   end
 end
 
+module ActionControllerMock
+  class Base
+    def render(_)
+      [:base]
+    end
+
+    def render_to_string
+    end
+
+    def self.after_action(_)
+    end
+  end
+end
+
 class PdfHelperTest < ActionController::TestCase
+  module SomePatch
+    def render(_)
+      super.tap do |s|
+        s << :patched
+      end
+    end
+  end
+
   def setup
     @ac = ActionController::Base.new
   end
@@ -22,4 +44,45 @@ def teardown
                        :header => { :html => { :template => 'hf.html.erb' } })
     assert_match %r{^file:\/\/\/.*wicked_header_pdf.*\.html}, options[:header][:html][:url]
   end
+
+  test 'should not interfere with already prepended patches' do
+    # Emulate railtie
+    if Rails::VERSION::MAJOR >= 5
+      # this spec tests the following:
+      # if another gem prepends a render method to ActionController::Base
+      # before wicked_pdf does, does calling render trigger an infinite loop?
+      # this spec fails with 6392bea1fe3a41682dfd7c20fd9c179b5a758f59 because PdfHelper
+      # aliases the render method prepended by the other gem to render_without_pdf, then
+      # base_evals its own definition of render, which calls render_with_pdf -> render_without_pdf.
+      # If the other gem uses the prepend inhertinance pattern (calling super instead of aliasing),
+      # when it calls super it calls the base_eval'd version of render instead of going up the
+      # inheritance chain, causing an infinite loop.
+
+      # This fiddling with consts is required to get around the fact that PdfHelper checks
+      # that it is being prepended to ActionController::Base
+      OriginalBase = ActionController::Base
+      ActionController.send(:remove_const, :Base)
+      ActionController.const_set(:Base, ActionControllerMock::Base)
+
+      # Emulate another gem being loaded before wicked
+      ActionController::Base.prepend(SomePatch)
+      ActionController::Base.prepend(::WickedPdf::PdfHelper)
+
+      begin
+        # test that wicked's render method is actually called
+        ac = ActionController::Base.new
+        ac.expects(:render_with_wicked_pdf)
+        ac.render(:cats)
+
+        # test that calling render does not trigger infinite loop
+        ac = ActionController::Base.new
+        assert_equal [:base, :patched], ac.render(:cats)
+      rescue SystemStackError
+        assert_equal true, false # force spec failure
+      ensure
+        ActionController.send(:remove_const, :Base)
+        ActionController.const_set(:Base, OriginalBase)
+      end
+    end
+  end
 end