From dd829df07e632209404b025423f57d63148d0867 Mon Sep 17 00:00:00 2001
From: Marek Kirejczyk <marekkirejczyk@users.noreply.github.com>
Date: Sat, 21 May 2016 14:14:22 +0200
Subject: [PATCH] Fix Hash#from_xml with frozen strings (#24718)
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* Hash#from_xml works with frozen strings

Fixes #24647

* Fix rexml engine test

[Marek Kirejczyk + Rafael Mendonça França]
---
 .../lib/active_support/xml_mini/rexml.rb      |  4 +--
 .../test/xml_mini/rexml_engine_test.rb        | 26 +++++++++++++------
 2 files changed, 19 insertions(+), 11 deletions(-)

diff --git a/activesupport/lib/active_support/xml_mini/rexml.rb b/activesupport/lib/active_support/xml_mini/rexml.rb
index 924ed72345..95af5af2c0 100644
--- a/activesupport/lib/active_support/xml_mini/rexml.rb
+++ b/activesupport/lib/active_support/xml_mini/rexml.rb
@@ -20,11 +20,9 @@ module ActiveSupport
         data = StringIO.new(data || '')
       end
 
-      char = data.getc
-      if char.nil?
+      if data.eof?
         {}
       else
-        data.ungetc(char)
         silence_warnings { require 'rexml/document' } unless defined?(REXML::Document)
         doc = REXML::Document.new(data)
 
diff --git a/activesupport/test/xml_mini/rexml_engine_test.rb b/activesupport/test/xml_mini/rexml_engine_test.rb
index f0067ca656..6e9ce7ac11 100644
--- a/activesupport/test/xml_mini/rexml_engine_test.rb
+++ b/activesupport/test/xml_mini/rexml_engine_test.rb
@@ -22,14 +22,24 @@ class REXMLEngineTest < ActiveSupport::TestCase
       morning
     </root>
     eoxml
-    assert_equal_rexml(io)
+    hash = ActiveSupport::XmlMini.parse(io)
+    assert hash.has_key?('root')
+    assert hash['root'].has_key?('products')
+    assert_match "good", hash['root']['__content__']
+    products = hash['root']['products']    
+    assert products.has_key?("__content__")    
+    assert_match 'hello everyone', products['__content__']
+  end
+
+  def test_parse_from_empty_string
+    ActiveSupport::XmlMini.backend = 'REXML'
+    assert_equal({}, ActiveSupport::XmlMini.parse(""))
+  end
+
+  def test_parse_from_frozen_string
+    ActiveSupport::XmlMini.backend = 'REXML'
+    xml_string = "<root></root>".freeze
+    assert_equal({"root" => {}}, ActiveSupport::XmlMini.parse(xml_string))
   end
 
-  private
-    def assert_equal_rexml(xml)
-      parsed_xml = ActiveSupport::XmlMini.parse(xml)
-      xml.rewind if xml.respond_to?(:rewind)
-      hash = ActiveSupport::XmlMini.with_backend('REXML') { ActiveSupport::XmlMini.parse(xml) }
-      assert_equal(hash, parsed_xml)
-    end
 end