1 files changed, 21 insertions, 0 deletions
diff --git a/spec/ruby/library/stringio/shared/write.rb b/spec/ruby/library/stringio/shared/write.rb
index d9c21028e0..b91e6ecec1 100644
--- a/spec/ruby/library/stringio/shared/write.rb
+++ b/spec/ruby/library/stringio/shared/write.rb
@@ -88,6 +88,27 @@ describe :stringio_write_string, shared: true do
     @io.write "fghi"
     @io.string.should == "12fghi"
   end
+
+  it "transcodes the given string when the external encoding is set and neither is BINARY" do
+    utf8_str = "hello"
+    io = StringIO.new.set_encoding(Encoding::UTF_16BE)
+    io.external_encoding.should == Encoding::UTF_16BE
+
+    io.send(@method, utf8_str)
+
+    expected = [0, 104, 0, 101, 0, 108, 0, 108, 0, 111] # UTF-16BE bytes for "hello"
+    io.string.bytes.should == expected
+  end
+
+  it "does not transcode the given string when the external encoding is set and the string encoding is BINARY" do
+    str = "été".b
+    io = StringIO.new.set_encoding(Encoding::UTF_16BE)
+    io.external_encoding.should == Encoding::UTF_16BE
+
+    io.send(@method, str)
+
+    io.string.bytes.should == str.bytes
+  end
 end
 
 describe :stringio_write_not_writable, shared: true do