* lib/csv.rb: Optimize header hashes by freezing string keys.

  [ruby-core:58510]



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@43825 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 6 insertions, 1 deletions

diff --git a/test/csv/test_row.rb b/test/csv/test_row.rb
index 697c7d56c8..a097fc7200 100755
--- a/test/csv/test_row.rb
+++ b/test/csv/test_row.rb
@@ -297,7 +297,12 @@ class TestCSV::Row < TestCSV
   end
 
   def test_to_hash
-    assert_equal({"A" => nil, "B" => 2, "C" => 3}, @row.to_hash)
+    hash = @row.to_hash
+    assert_equal({"A" => nil, "B" => 2, "C" => 3}, hash)
+    hash.keys.each_with_index do |string_key, h|
+      assert_predicate(string_key, :frozen?)
+      assert_same(string_key, @row.headers[h])
+    end
   end
 
   def test_to_csv