tests: fix upload tests.

test/test_helpers/upload_test_helper.rb

@@ -1,23 +1,10 @@
 module UploadTestHelper
-  def upload_file(path, content_type, filename)
-    tempfile = Tempfile.new(filename)
-    FileUtils.copy_file(path, tempfile.path)
+  def upload_file(path)
+    file = Tempfile.new(binmode: true)
+    IO.copy_stream("#{Rails.root}/#{path}", file.path)
+    uploaded_file = ActionDispatch::Http::UploadedFile.new(tempfile: file, filename: File.basename(path))
 
-    (class << tempfile; self; end).class_eval do
-      alias local_path path
-      define_method(:tempfile) {self}
-      define_method(:original_filename) {filename}
-      define_method(:content_type) {content_type}
-    end
-
-    tempfile
-  end
-
-  def upload_jpeg(path)
-    upload_file(path, "image/jpeg", File.basename(path))
-  end
-
-  def upload_zip(path)
-    upload_file(path, "application/zip", File.basename(path))
+    yield uploaded_file if block_given?
+    uploaded_file
   end
 end