ruby/lib/test/unit.rb

require 'test/unit/testcase'
require 'test/unit/autorunner'

module Test # :nodoc:
  #
  # = Test::Unit - Ruby Unit Testing Framework
  # 
  # == Introduction
  # 
  # Unit testing is making waves all over the place, largely due to the
  # fact that it is a core practice of XP. While XP is great, unit testing
  # has been around for a long time and has always been a good idea. One
  # of the keys to good unit testing, though, is not just writing tests,
  # but having tests. What's the difference? Well, if you just _write_ a
  # test and throw it away, you have no guarantee that something won't
  # change later which breaks your code. If, on the other hand, you _have_
  # tests (obviously you have to write them first), and run them as often
  # as possible, you slowly build up a wall of things that cannot break
  # without you immediately knowing about it. This is when unit testing
  # hits its peak usefulness.
  # 
  # Enter Test::Unit, a framework for unit testing in Ruby, helping you to
  # design, debug and evaluate your code by making it easy to write and
  # have tests for it.
  # 
  # 
  # == Notes
  # 
  # Test::Unit has grown out of and superceded Lapidary.
  # 
  # 
  # == Feedback
  # 
  # I like (and do my best to practice) XP, so I value early releases,
  # user feedback, and clean, simple, expressive code. There is always
  # room for improvement in everything I do, and Test::Unit is no
  # exception. Please, let me know what you think of Test::Unit as it
  # stands, and what you'd like to see expanded/changed/improved/etc. If
  # you find a bug, let me know ASAP; one good way to let me know what the
  # bug is is to submit a new test that catches it :-) Also, I'd love to
  # hear about any successes you have with Test::Unit, and any
  # documentation you might add will be greatly appreciated. My contact
  # info is below.
  # 
  # 
  # == Contact Information
  # 
  # A lot of discussion happens about Ruby in general on the ruby-talk
  # mailing list (http://www.ruby-lang.org/en/ml.html), and you can ask
  # any questions you might have there. I monitor the list, as do many
  # other helpful Rubyists, and you're sure to get a quick answer. Of
  # course, you're also welcome to email me (Nathaniel Talbott) directly
  # at mailto:testunit@talbott.ws, and I'll do my best to help you out.
  # 
  # 
  # == Credits
  # 
  # I'd like to thank...
  # 
  # Matz, for a great language!
  # 
  # Masaki Suketa, for his work on RubyUnit, which filled a vital need in
  # the Ruby world for a very long time. I'm also grateful for his help in
  # polishing Test::Unit and getting the RubyUnit compatibility layer
  # right. His graciousness in allowing Test::Unit to supercede RubyUnit
  # continues to be a challenge to me to be more willing to defer my own
  # rights.
  # 
  # Ken McKinlay, for his interest and work on unit testing, and for his
  # willingness to dialog about it. He was also a great help in pointing
  # out some of the holes in the RubyUnit compatibility layer.
  # 
  # Dave Thomas, for the original idea that led to the extremely simple
  # "require 'test/unit'", plus his code to improve it even more by
  # allowing the selection of tests from the command-line. Also, without
  # RDoc, the documentation for Test::Unit would stink a lot more than it
  # does now.
  # 
  # Everyone who's helped out with bug reports, feature ideas,
  # encouragement to continue, etc. It's a real privilege to be a part of
  # the Ruby community.
  # 
  # The guys at RoleModel Software, for putting up with me repeating, "But
  # this would be so much easier in Ruby!" whenever we're coding in Java.
  # 
  # My Creator, for giving me life, and giving it more abundantly.
  # 
  # 
  # == License
  # 
  # Test::Unit is copyright (c) 2000-2003 Nathaniel Talbott. It is free
  # software, and is distributed under the Ruby license. See the COPYING
  # file in the standard Ruby distribution for details.
  # 
  # 
  # == Warranty
  # 
  # This software is provided "as is" and without any express or
  # implied warranties, including, without limitation, the implied
  # warranties of merchantibility and fitness for a particular
  # purpose.
  # 
  # 
  # == Author
  # 
  # Nathaniel Talbott.
  # Copyright (c) 2000-2003, Nathaniel Talbott
  #
  # ----
  #
  # = Usage
  #
  # The general idea behind unit testing is that you write a _test_
  # _method_ that makes certain _assertions_ about your code, working
  # against a _test_ _fixture_. A bunch of these _test_ _methods_ are
  # bundled up into a _test_ _suite_ and can be run any time the
  # developer wants. The results of a run are gathered in a _test_
  # _result_ and displayed to the user through some UI. So, lets break
  # this down and see how Test::Unit provides each of these necessary
  # pieces.
  #
  #
  # == Assertions
  #
  # These are the heart of the framework. Think of an assertion as a
  # statement of expected outcome, i.e. "I assert that x should be equal
  # to y". If, when the assertion is executed, it turns out to be
  # correct, nothing happens, and life is good. If, on the other hand,
  # your assertion turns out to be false, an error is propagated with
  # pertinent information so that you can go back and make your
  # assertion succeed, and, once again, life is good. For an explanation
  # of the current assertions, see Test::Unit::Assertions.
  #
  #
  # == Test Method & Test Fixture
  #
  # Obviously, these assertions have to be called within a context that
  # knows about them and can do something meaningful with their
  # pass/fail value. Also, it's handy to collect a bunch of related
  # tests, each test represented by a method, into a common test class
  # that knows how to run them. The tests will be in a separate class
  # from the code they're testing for a couple of reasons. First of all,
  # it allows your code to stay uncluttered with test code, making it
  # easier to maintain. Second, it allows the tests to be stripped out
  # for deployment, since they're really there for you, the developer,
  # and your users don't need them. Third, and most importantly, it
  # allows you to set up a common test fixture for your tests to run
  # against.
  #
  # What's a test fixture? Well, tests do not live in a vacuum; rather,
  # they're run against the code they are testing. Often, a collection
  # of tests will run against a common set of data, also called a
  # fixture. If they're all bundled into the same test class, they can
  # all share the setting up and tearing down of that data, eliminating
  # unnecessary duplication and making it much easier to add related
  # tests.
  #
  # Test::Unit::TestCase wraps up a collection of test methods together
  # and allows you to easily set up and tear down the same test fixture
  # for each test. This is done by overriding #setup and/or #teardown,
  # which will be called before and after each test method that is
  # run. The TestCase also knows how to collect the results of your
  # assertions into a Test::Unit::TestResult, which can then be reported
  # back to you... but I'm getting ahead of myself. To write a test,
  # follow these steps:
  #
  # * Make sure Test::Unit is in your library path.
  # * require 'test/unit' in your test script.
  # * Create a class that subclasses Test::Unit::TestCase.
  # * Add a method that begins with "test" to your class.
  # * Make assertions in your test method.
  # * Optionally define #setup and/or #teardown to set up and/or tear
  #   down your common test fixture.
  # * You can now run your test as you would any other Ruby
  #   script... try it and see!
  #
  # A really simple test might look like this (#setup and #teardown are
  # commented out to indicate that they are completely optional):
  #
  #     require 'test/unit'
  #     
  #     class TC_MyTest < Test::Unit::TestCase
  #       # def setup
  #       # end
  #     
  #       # def teardown
  #       # end
  #     
  #       def test_fail
  #         assert(false, 'Assertion was false.')
  #       end
  #     end
  #
  #
  # == Test Runners
  #
  # So, now you have this great test class, but you still need a way to
  # run it and view any failures that occur during the run. This is
  # where Test::Unit::UI::Console::TestRunner (and others, such as
  # Test::Unit::UI::GTK::TestRunner) comes into play. The console test
  # runner is automatically invoked for you if you require 'test/unit'
  # and simply run the file. To use another runner, or to manually
  # invoke a runner, simply call its run class method and pass in an
  # object that responds to the suite message with a
  # Test::Unit::TestSuite. This can be as simple as passing in your
  # TestCase class (which has a class suite method). It might look
  # something like this:
  #
  #    require 'test/unit/ui/console/testrunner'
  #    Test::Unit::UI::Console::TestRunner.run(TC_MyTest)
  #
  #
  # == Test Suite
  #
  # As more and more unit tests accumulate for a given project, it
  # becomes a real drag running them one at a time, and it also
  # introduces the potential to overlook a failing test because you
  # forget to run it. Suddenly it becomes very handy that the
  # TestRunners can take any object that returns a Test::Unit::TestSuite
  # in response to a suite method. The TestSuite can, in turn, contain
  # other TestSuites or individual tests (typically created by a
  # TestCase). In other words, you can easily wrap up a group of
  # TestCases and TestSuites like this:
  #
  #  require 'test/unit/testsuite'
  #  require 'tc_myfirsttests'
  #  require 'tc_moretestsbyme'
  #  require 'ts_anothersetoftests'
  #
  #  class TS_MyTests
  #    def self.suite
  #      suite = Test::Unit::TestSuite.new
  #      suite << TC_MyFirstTests.suite
  #      suite << TC_MoreTestsByMe.suite
  #      suite << TS_AnotherSetOfTests.suite
  #      return suite
  #    end
  #  end
  #  Test::Unit::UI::Console::TestRunner.run(TS_MyTests)
  #
  # Now, this is a bit cumbersome, so Test::Unit does a little bit more
  # for you, by wrapping these up automatically when you require
  # 'test/unit'. What does this mean? It means you could write the above
  # test case like this instead:
  #
  #  require 'test/unit'
  #  require 'tc_myfirsttests'
  #  require 'tc_moretestsbyme'
  #  require 'ts_anothersetoftests'
  #
  # Test::Unit is smart enough to find all the test cases existing in
  # the ObjectSpace and wrap them up into a suite for you. It then runs
  # the dynamic suite using the console TestRunner.
  #
  #
  # == Questions?
  #
  # I'd really like to get feedback from all levels of Ruby
  # practitioners about typos, grammatical errors, unclear statements,
  # missing points, etc., in this document (or any other).
  #

  module Unit
    # If set to false Test::Unit will not automatically run at exit.
    def self.run=(flag)
      @run = flag
    end

    # Automatically run tests at exit?
    def self.run?
      @run ||= false
    end
  end
end

at_exit do
  unless $! || Test::Unit.run?
    exit Test::Unit::AutoRunner.run
  end
end