Helpful Additions To Test::Unit

Doing a lot of rails work, I’m getting a good feel for testing in ruby and rails. Here are some tricks / snippets I use :

assert_raises takes a string and/or a class

I want to be able to write

one ='one')

I’ve done this a few times, but I think cruisecontrol.rb’s implementation is the most robust :

  def assert_raises(arg1 = nil, arg2 = nil)
    expected_error = arg1.is_a?(Exception) ? arg1 : nil
    expected_class = arg1.is_a?(Class) ? arg1 : nil
    expected_message = arg1.is_a?(String) ? arg1 : arg2
      fail "expected error was not raised"
    rescue Test::Unit::AssertionFailedError
    rescue => e
      raise if e.message == "expected error was not raised"
      assert_equal(expected_error, e) if expected_error
      assert_equal(expected_class, e.class, "Unexpected error type raised") if expected_class
      assert_equal(expected_message, e.message, "Unexpected error message") if expected_message.is_a? String
      assert_matched(expected_message, e.message, "Unexpected error message") if expected_message.is_a? Regexp

h2. assert_equal_sets

In Java, I used to push things into sets and compare them when I didn’t care about order. In ruby, I sometimes use assert_equal_sets. It does a compare of two arrays independent of order. So

  assert_equal_sets [1, 3, 5], [3, 5, 1]   # passes
  assert_equal_sets [2, 3], [3, 4]    # fails

class Array
  def reorder_like!(other)
    tmp = dup
    other.each {|x| self

h2. file_sandbox for testing against the file system

After dragging this code around me for the last 6 or 7 projects I’ve been on, I finally packaged it up as a gem . It lets you write code like :

in_sandbox do |sandbox| :file => 'b/a.txt', :with_contents => 'some stuff'
  assert_equal 'some_stuff', + '/b/a.txt')

Basically it creates a temporary directory for you to muck about in. After the block is ended (or teardown is called on your test) that directory and everything in it is guaranteed to be cleaned up. It also has a bunch of methods to make file based things easier like creating a file, etc.

Install it with “gem install file_sandbox”

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