Fill foo(x)

gistfile1.rb

require 'test/unit'

def foo(x)
end

class TestFoo < Test::Unit::TestCase

  def test_smoke_scenario
    assert_equal 1, foo(foo(-1))
    assert_equal -5, foo(foo(5))
    assert_equal 0, foo(foo(0))
    assert_equal 10, foo(foo(foo(foo(10))))
    (1..100).each{|i| assert_equal -i, foo(foo(i))}
  end
end