```ruby
require File.dirname(__FILE__) + '/../../spec_helper'

describe "IO#printf" do
  before :each do
    @io = IO.new STDOUT.fileno
  end
  
fails_on :jruby
  it "writes the #sprintf formatted string to the file descriptor" do
    lambda {
      @io.printf "%s\n", "look ma, no hands"
    }.should output_to_fd("look ma, no hands\n", @io)
  end
end
end
```

Fix my oops; missing 'do' for the fails_on
user
```ruby
require File.dirname(__FILE__) + '/../../spec_helper'

describe "IO#printf" do
  before :each do
    @io = IO.new STDOUT.fileno
  end
  
fails_on :jruby do
  it "writes the #sprintf formatted string to the file descriptor" do
    lambda {
      @io.printf "%s\n", "look ma, no hands"
    }.should output_to_fd("look ma, no hands\n", @io)
  end
end
end
```
assistant