Shorten stack trace file names

after.txt

  1) Error:
test_0001_should generate form with method=get(integration search_form_for):
ArgumentError: wrong number of arguments (1 for 2)
    /spec/minitest_helper.rb:68:in `block (3 levels) in formed_class'
    /gems/actionpack-3.2.9/lib/action_dispatch/routing/polymorphic_routes.rb:129:in `polymorphic_url'
    /gems/actionpack-3.2.9/lib/action_dispatch/routing/polymorphic_routes.rb:135:in `polymorphic_path'
    /gems/actionpack-3.2.9/lib/action_view/helpers/form_helper.rb:397:in `apply_form_for_options!'
    /gems/actionpack-3.2.9/lib/action_view/helpers/form_helper.rb:370:in `form_for'
    /lib/mundane-search/view_helpers.rb:10:in `search_form_for'
    /spec/search_form_for_integration_spec.rb:15:in `block (2 levels) in <top (required)>'

before.txt

  1) Error:
test_0001_should generate form with method=get(integration search_form_for):
ArgumentError: wrong number of arguments (1 for 2)
    /Users/samsm/Repositories/mine/mundane-search/spec/minitest_helper.rb:68:in `block (3 levels) in formed_class'
    /Users/samsm/.rvm/gems/ruby-1.9.3-p374@mundane-search/gems/actionpack-3.2.9/lib/action_dispatch/routing/polymorphic_routes.rb:129:in `polymorphic_url'
    /Users/samsm/.rvm/gems/ruby-1.9.3-p374@mundane-search/gems/actionpack-3.2.9/lib/action_dispatch/routing/polymorphic_routes.rb:135:in `polymorphic_path'
    /Users/samsm/.rvm/gems/ruby-1.9.3-p374@mundane-search/gems/actionpack-3.2.9/lib/action_view/helpers/form_helper.rb:397:in `apply_form_for_options!'
    /Users/samsm/.rvm/gems/ruby-1.9.3-p374@mundane-search/gems/actionpack-3.2.9/lib/action_view/helpers/form_helper.rb:370:in `form_for'
    /Users/samsm/Repositories/mine/mundane-search/lib/mundane-search/view_helpers.rb:10:in `search_form_for'
    /Users/samsm/Repositories/mine/mundane-search/spec/search_form_for_integration_spec.rb:15:in `block (2 levels) in <top (required)>'

in_minitest_helper.rb

class AgressiveBacktraceFilter < Minitest::BacktraceFilter
  def gem_paths
    return @gem_paths if @gem_paths
    raw_paths = `gem env gempath`
    @gem_paths = raw_paths.split(':')
  end

  def project_path
    @project_path ||= File.expand_path(File.dirname(__FILE__) + "/../")
  end

  def filter_paths
    gem_paths + [project_path]
  end

  def filter(bt)
    original_filter = super(bt)
    original_filter.collect do |line|
      filter_paths.inject(line) do |sum, path|
        sum.sub(/\A#{path}/,'')
      end
    end
  end
end

Minitest.backtrace_filter = AgressiveBacktraceFilter.new