SvgSurface creates an empty svg file

[EriKWDev]

I'm trying to draw the same surface as in the high-level x11 window example using the code below.
While I can create a nice png image with

surface.write_to_png "test.png"

... I can't find a way to write it to svg. There doesn't seem to be a write_to_svg ..?
When I run the code below, however, an empty "test.svg" is written

require "cairo"

module SvgCreation
  include Cairo

  def self.main
    surface = Cairo::SvgSurface.new "test.svg", 400, 300
    # surface.restrict_to_version Cairo::SvgVersion::V_1_2
    context = Cairo::Context.new surface


    context.set_source_rgba 1.0, 0.0, 1.0, 1.0
    context.rectangle 0.0, 0.0, 400.0, 300.0
    context.fill

    context.set_source_rgb 0.0, 0.0, 0.0
    context.move_to 0.0, 0.0
    context.line_to 400.0, 300.0
    context.move_to 400.0, 0.0
    context.line_to 0.0, 300.0
    context.line_width = 10.0
    context.stroke

    context.rectangle 0.0, 0.0, 200.0, 150.0
    context.set_source_rgba 1.0, 0.0, 0.0, 0.80
    context.fill

    context.rectangle 0.0, 150.0, 200.0, 150.0
    context.set_source_rgba 0.0, 1.0, 0.0, 0.60
    context.fill

    context.rectangle 200.0, 0.0, 200.0, 150.0
    context.set_source_rgba 0.0, 0.0, 1.0, 0.40
    context.fill

    # surface.write_to_png "test.png"
  end

  main
end

Is there a close/destroy/save method or something that I'm missing?

[tamas-szekeres-ecom]

Just call surface.finish.

Also a good idea to call GC when program exits:

at_exit do
  GC.collect
end

module Program
# ...
end

[EriKWDev]

Just call surface.finish.

That was it xP Thanks!