require File.expand_path('../../../spec_helper', __FILE__)

ruby_version_is "1.9" do
  describe "IO#ungetbyte" do
    before :each do
      @name = tmp("io_ungetbyte")
      touch(@name) { |f| f.write "a" }
      @io = new_io @name, "r"
    end

    after :each do
      @io.close unless @io.closed?
      rm_r @name
    end

    it "does nothing when passed nil" do
      @io.ungetbyte(nil).should be_nil
      @io.getbyte.should == 97
    end

    it "puts back each byte in a String argument" do
      @io.ungetbyte("cat").should be_nil
      @io.getbyte.should == 99
      @io.getbyte.should == 97
      @io.getbyte.should == 116
      @io.getbyte.should == 97
    end

    it "calls #to_str to convert the argument" do
      str = mock("io ungetbyte")
      str.should_receive(:to_str).and_return("dog")

      @io.ungetbyte(str).should be_nil
      @io.getbyte.should == 100
      @io.getbyte.should == 111
      @io.getbyte.should == 103
      @io.getbyte.should == 97
    end

    it "puts back one byte for an Integer argument" do
      @io.ungetbyte(4095).should be_nil
      @io.getbyte.should == 255
    end

    it "raises an IOError if the IO is closed" do
      @io.close
      lambda { @io.ungetbyte(42) }.should raise_error(IOError)
    end
  end
end