Fix #5440 - multiple render_to_string breaks partials formats

This fixes situation where rendering template to string
sets `rendered_format` to the format rendered there.
This is ok to have consistent formats rendered in partials,
but it breaks on next renders if format is explicitly set
or on last render where default format does not necessarily
need to be the format of first rendered template.

6 files changed, 31 insertions, 0 deletions

diff --git a/actionpack/lib/abstract_controller/rendering.rb b/actionpack/lib/abstract_controller/rendering.rb
index 9019c07bca..f74fd6ac4a 100644
--- a/actionpack/lib/abstract_controller/rendering.rb
+++ b/actionpack/lib/abstract_controller/rendering.rb
@@ -106,6 +106,7 @@ module AbstractController
     # Find and renders a template based on the options given.
     # :api: private
     def _render_template(options) #:nodoc:
+      lookup_context.rendered_format = nil if options[:formats]
       view_renderer.render(view_context, options)
     end
 
diff --git a/actionpack/test/controller/render_test.rb b/actionpack/test/controller/render_test.rb
index e9b0fe7008..daa2676e22 100644
--- a/actionpack/test/controller/render_test.rb
+++ b/actionpack/test/controller/render_test.rb
@@ -549,6 +549,17 @@ class TestController < ActionController::Base
     render :template => "test/hello_world"
   end
 
+  def render_to_string_with_template_and_html_partial
+    @text = render_to_string :template => "test/with_partial", :formats => [:text]
+    @html = render_to_string :template => "test/with_partial", :formats => [:html]
+    render :template => "test/with_html_partial"
+  end
+
+  def render_to_string_and_render_with_different_formats
+    @html = render_to_string :template => "test/with_partial", :formats => [:html]
+    render :template => "test/with_partial", :formats => [:text]
+  end
+
   def partial_with_counter
     render :partial => "counter", :locals => { :counter_counter => 5 }
   end
@@ -1263,6 +1274,21 @@ class RenderTest < ActionController::TestCase
     assert_equal "text/html", @response.content_type
   end
 
+  def test_render_to_string_with_template_and_html_partial
+    get :render_to_string_with_template_and_html_partial
+    assert_equal "**only partial**\n", assigns(:text)
+    assert_equal "<strong>only partial</strong>\n", assigns(:html)
+    assert_equal "<strong>only html partial</strong>\n", @response.body
+    assert_equal "text/html", @response.content_type
+  end
+
+  def test_render_to_string_and_render_with_different_formats
+    get :render_to_string_and_render_with_different_formats
+    assert_equal "<strong>only partial</strong>\n", assigns(:html)
+    assert_equal "**only partial**\n", @response.body
+    assert_equal "text/plain", @response.content_type
+  end
+
   def test_partial_with_counter
     get :partial_with_counter
     assert_equal "5", @response.body
diff --git a/actionpack/test/fixtures/test/_partial_only_html.html b/actionpack/test/fixtures/test/_partial_only_html.html
new file mode 100644
index 0000000000..d2d630bd40
--- /dev/null
+++ b/actionpack/test/fixtures/test/_partial_only_html.html
@@ -0,0 +1 @@
+only html partial
\ No newline at end of file
diff --git a/actionpack/test/fixtures/test/with_html_partial.html.erb b/actionpack/test/fixtures/test/with_html_partial.html.erb
new file mode 100644
index 0000000000..d84d909d64
--- /dev/null
+++ b/actionpack/test/fixtures/test/with_html_partial.html.erb
@@ -0,0 +1 @@
+<strong><%= render :partial => "partial_only_html" %></strong>
diff --git a/actionpack/test/fixtures/test/with_partial.html.erb b/actionpack/test/fixtures/test/with_partial.html.erb
new file mode 100644
index 0000000000..7502364cf5
--- /dev/null
+++ b/actionpack/test/fixtures/test/with_partial.html.erb
@@ -0,0 +1 @@
+<strong><%= render :partial => "partial_only" %></strong>
diff --git a/actionpack/test/fixtures/test/with_partial.text.erb b/actionpack/test/fixtures/test/with_partial.text.erb
new file mode 100644
index 0000000000..5f068ebf27
--- /dev/null
+++ b/actionpack/test/fixtures/test/with_partial.text.erb
@@ -0,0 +1 @@
+**<%= render :partial => "partial_only" %>**