1 files changed, 14 insertions, 3 deletions
diff --git a/spec/ruby/core/io/syswrite_spec.rb b/spec/ruby/core/io/syswrite_spec.rb
index 1b1477bc6e..8bf61a27c3 100644
--- a/spec/ruby/core/io/syswrite_spec.rb
+++ b/spec/ruby/core/io/syswrite_spec.rb
@@ -29,15 +29,25 @@ describe "IO#syswrite on a file" do
     end
   end
 
+  it "does not modify the passed argument" do
+    File.open(@filename, "w") do |f|
+      f.set_encoding(Encoding::IBM437)
+      # A character whose codepoint differs between UTF-8 and IBM437
+      f.syswrite("ƒ".freeze)
+    end
+
+    File.binread(@filename).bytes.should == [198, 146]
+  end
+
   it "warns if called immediately after a buffered IO#write" do
     @file.write("abcde")
-    lambda { @file.syswrite("fghij") }.should complain(/syswrite/)
+    -> { @file.syswrite("fghij") }.should complain(/syswrite/)
   end
 
   it "does not warn if called after IO#write with intervening IO#sysread" do
     @file.syswrite("abcde")
     @file.sysread(5)
-    lambda { @file.syswrite("fghij") }.should_not complain
+    -> { @file.syswrite("fghij") }.should_not complain
   end
 
   it "writes to the actual file position when called after buffered IO#read" do
@@ -55,7 +65,7 @@ describe "IO#syswrite on a pipe" do
     r, w = IO.pipe
     begin
       w.nonblock = true
-      larger_than_pipe_capacity = 100 * 1024
+      larger_than_pipe_capacity = 2 * 1024 * 1024
       written = w.syswrite("a"*larger_than_pipe_capacity)
       written.should > 0
       written.should < larger_than_pipe_capacity
@@ -68,4 +78,5 @@ end
 
 describe "IO#syswrite" do
   it_behaves_like :io_write, :syswrite
+  it_behaves_like :io_write_no_transcode, :syswrite
 end