1 files changed, 18 insertions, 4 deletions
diff --git a/spec/ruby/library/stringio/puts_spec.rb b/spec/ruby/library/stringio/puts_spec.rb
index a9f289a5a5..054ec8227f 100644
--- a/spec/ruby/library/stringio/puts_spec.rb
+++ b/spec/ruby/library/stringio/puts_spec.rb
@@ -101,6 +101,20 @@ describe "StringIO#puts when passed 1 or more objects" do
     @io.puts ''
     @io.string.should == "\n"
   end
+
+  it "handles concurrent writes correctly" do
+    n = 8
+    go = false
+    threads = n.times.map { |i|
+      Thread.new {
+        Thread.pass until go
+        @io.puts i
+      }
+    }
+    go = true
+    threads.each(&:join)
+    @io.string.size.should == n.times.map { |i| "#{i}\n" }.join.size
+  end
 end
 
 describe "StringIO#puts when passed no arguments" do
@@ -131,7 +145,7 @@ end
 
 describe "StringIO#puts when in append mode" do
   before :each do
-    @io = StringIO.new("example", "a")
+    @io = StringIO.new(+"example", "a")
   end
 
   it "appends the passed argument to the end of self" do
@@ -150,10 +164,10 @@ end
 
 describe "StringIO#puts when self is not writable" do
   it "raises an IOError" do
-    io = StringIO.new("test", "r")
+    io = StringIO.new(+"test", "r")
     -> { io.puts }.should raise_error(IOError)
 
-    io = StringIO.new("test")
+    io = StringIO.new(+"test")
     io.close_write
     -> { io.puts }.should raise_error(IOError)
   end
@@ -161,7 +175,7 @@ end
 
 describe "StringIO#puts when passed an encoded string" do
   it "stores the bytes unmodified" do
-    io = StringIO.new("")
+    io = StringIO.new(+"")
     io.puts "\x00\x01\x02"
     io.puts "æåø"