1 files changed, 14 insertions, 0 deletions
diff --git a/spec/ruby/library/stringio/binmode_spec.rb b/spec/ruby/library/stringio/binmode_spec.rb
index 5d9a8c41df..83178787f3 100644
--- a/spec/ruby/library/stringio/binmode_spec.rb
+++ b/spec/ruby/library/stringio/binmode_spec.rb
@@ -6,4 +6,18 @@ describe "StringIO#binmode" do
     io = StringIO.new("example")
     io.binmode.should equal(io)
   end
+
+  it "changes external encoding to BINARY" do
+    io = StringIO.new
+    io.external_encoding.should == Encoding.find('locale')
+    io.binmode
+    io.external_encoding.should == Encoding::BINARY
+  end
+
+  it "does not set internal encoding" do
+    io = StringIO.new
+    io.internal_encoding.should == nil
+    io.binmode
+    io.internal_encoding.should == nil
+  end
 end