1 files changed, 25 insertions, 0 deletions
diff --git a/spec/ruby/library/stringio/external_encoding_spec.rb b/spec/ruby/library/stringio/external_encoding_spec.rb
new file mode 100644
index 0000000000..6c5edb1713
--- /dev/null
+++ b/spec/ruby/library/stringio/external_encoding_spec.rb
@@ -0,0 +1,25 @@
+require 'stringio'
+require_relative '../../spec_helper'
+
+describe "StringIO#external_encoding" do
+  it "gets the encoding of the underlying String" do
+    io = StringIO.new
+    io.set_encoding Encoding::EUC_JP
+    io.external_encoding.should == Encoding::EUC_JP
+  end
+
+  it "changes to match string if string's encoding is changed" do
+    io = StringIO.new
+    io.string.force_encoding(Encoding::EUC_JP)
+    io.external_encoding.should == Encoding::EUC_JP
+  end
+
+  it "does not set the encoding of its buffer string if the string is frozen" do
+    str = "foo".freeze
+    enc = str.encoding
+    io = StringIO.new(str)
+    io.set_encoding Encoding::EUC_JP
+    io.external_encoding.should == Encoding::EUC_JP
+    str.encoding.should == enc
+  end
+end