Ruby测试：在测试用例中打印

我是Ruby测试的新手，Google帮不了我

使用Test/Unit，如何打印实例变量，如

test "thing to happen" do
  do_stuff
  assert_equal "foo", @variable
  p @varible
end

Ruby可以将消息输出到test runner控制台：

test "thing to happen" do
  do_stuff
  assert_equal "foo", @variable, "@variable is #{@variable} when: things to happen"
  p @varible
end

---

该代码应该将@variable输出到控制台，除非断言失败。您的问题到底是什么？实例变量是在测试用例中还是在被测试对象中？