1 files changed, 17 insertions, 0 deletions
diff --git a/activesupport/test/deprecation_test.rb b/activesupport/test/deprecation_test.rb
index ee1c69502e..7aff56cbad 100644
--- a/activesupport/test/deprecation_test.rb
+++ b/activesupport/test/deprecation_test.rb
@@ -355,4 +355,21 @@ class DeprecationTest < ActiveSupport::TestCase
       end
       deprecator
     end
+
+    def capture(stream)
+      stream = stream.to_s
+      captured_stream = Tempfile.new(stream)
+      stream_io = eval("$#{stream}")
+      origin_stream = stream_io.dup
+      stream_io.reopen(captured_stream)
+
+      yield
+
+      stream_io.rewind
+      return captured_stream.read
+    ensure
+      captured_stream.close
+      captured_stream.unlink
+      stream_io.reopen(origin_stream)
+    end
 end