From 32b2942946edba6a288c6b992109598eeb626964 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Janko=20Marohni=C4=87?= <janko.marohnic@gmail.com>
Date: Sat, 23 Feb 2019 23:10:20 +0100
Subject: Restore UploadedFile compatibility with IO.copy_stream

In https://github.com/rails/rails/pull/28676 the `#to_path` method was
added to `ActionDispatch::Http::UploadedFile`. This broke usage with
`IO.copy_stream`:

  source = ActionDispatch::Http::UploadedFile.new(...)
  IO.copy_stream(source, destination)
  # ~> TypeError: can't convert ActionDispatch::Http::UploadedFile to IO (ActionDispatch::Http::UploadedFile#to_io gives Tempfile)

Normally `IO.copy_stream` just calls `#read` on the source object.
However, when `#to_path` is defined, `IO.copy_stream` calls `#to_io` in
order to retrieve the raw `File` object. In that case it trips up,
because `ActionDispatch::Http::UploadedFile#to_io` returned a `Tempfile`
object, which is not an `IO` subclass.

We fix this by having `#to_io` return an actual `File` object.
---
 actionpack/test/dispatch/uploaded_file_test.rb | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

(limited to 'actionpack/test')

diff --git a/actionpack/test/dispatch/uploaded_file_test.rb b/actionpack/test/dispatch/uploaded_file_test.rb
index e71c5cc629..03e5274541 100644
--- a/actionpack/test/dispatch/uploaded_file_test.rb
+++ b/actionpack/test/dispatch/uploaded_file_test.rb
@@ -2,6 +2,7 @@
 
 require "abstract_unit"
 require "tempfile"
+require "stringio"
 
 module ActionDispatch
   class UploadedFileTest < ActiveSupport::TestCase
@@ -49,10 +50,10 @@ module ActionDispatch
       assert_equal tf, uf.tempfile
     end
 
-    def test_to_io_returns_tempfile
+    def test_to_io_returns_file
       tf = Tempfile.new
       uf = Http::UploadedFile.new(tempfile: tf)
-      assert_equal tf, uf.to_io
+      assert_equal tf.to_io, uf.to_io
     end
 
     def test_delegates_path_to_tempfile
@@ -115,5 +116,15 @@ module ActionDispatch
       uf = Http::UploadedFile.new(tempfile: tf)
       assert_equal tf.to_path, uf.to_path
     end
+
+    def test_io_copy_stream
+      tf = Tempfile.new
+      tf << "thunderhorse"
+      tf.rewind
+      uf = Http::UploadedFile.new(tempfile: tf)
+      result = StringIO.new
+      IO.copy_stream(uf, result)
+      assert_equal "thunderhorse", result.string
+    end
   end
 end
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