# File test/test_rrdtool.rb, line 93
  def test_graph
    create_file
    create_data
    RRDtool.graph(
        [@g, "--title", " RubyRRD Demo", 
        "--start", "#{@start} + 1 h",
        "--end", "#{@start} + 1000 min",
        "--interlace", 
        "--imgformat", "PNG",
        "--width=450",
        "DEF:a=#{@f}:a:AVERAGE",
        "DEF:b=#{@f}:b:AVERAGE",
        "CDEF:line=TIME,2400,%,300,LT,a,UNKN,IF",
        "AREA:b#00b6e4:beta",
        "AREA:line#0022e9:alpha",
        "LINE3:line#ff0000"])
    assert File.exists?(@g)
  end