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Title
=====
Good morning everyone. My name is Rein Henrichs and this is Real World Ruby
Testing. Today, I'm going to talk to you about what you should use to test and
how you should write your tests. For those of you who don't write tests or
don't write them often, I'll talk briefly about *why* you should write tests.
Before I get started, I want to ask you all a few questions:
How many of you here by show of hands have never written a test before?
How many of you write tests every day?
For those of you who do write tests:
How many of you use Test::Unit?
How many of you use RSpec?
How many of you use Shoulda?
How many of you use something else?
Intro
=====
So this is me. I twitter and I blog. I work at PuppetLabs, the maker of Puppet
and Puppet related accessories. The slides for this talk are available for you
to follow along on your laptops if you would like.
rake spec
---------
This is the RSpec suite for Puppet. If you add in the specs that didn't run
because I'm not on FreeBSD, Debian, RHEL or AIX and so on, the total number of
examples is well over 9000.
Testing Frameworks
==================
There are a lot of testing frameworks out there in Ruby land. We're going to
look at the most popular ones briefly.
Test::Unit
==========
RSpec
=====
* Written by David Chelimsky, a core team of developers and dozens of contributors
Shoulda
=======
* Written by Tammer Saleh and Thoughtbot
Microtest
=========
* Written by Ryan Davis
Micronaut
=========
* Written by Chad Humphries of Relevance, Inc
Bacon
=====
* Written by Christian Neukirchen
Baretest
========
* Written by Stefan Rusterholz
Bacon
=====
* Written by Justin Knowlden
Choosing a Testing Framework
============================
Now that I've shown you all of these testing frameworks, I'm going to say
something that might surprise you:
"Your choice of testing framework isn't a significant contributor to the
quality of your tests"
What really matters is familiarity and expressiveness. Familiarity is your own
familiarity with your chosen framework, your team's familiarity and your
community' familiarity. It's how long it will take you to find answers to
difficult testing frameworks. Expressiveness is the quality of feedback
provided or enabled by the framework. All of these frameworks can provide good
feedback, but some may make it easier for you.
Why We Test
===========
In Test-Driven Development by example, Kent Beck cites Ross Jeffries' phrase
"Clean code that works" as the goal of Test Driven Development. I would like to
propose two other reasons for writing tests: we write tests to drive
development and manage change.
There are two important reasons to write tests, confidence and communication.
Tests give us confidence in the present and for the future. In the present,
good tests give us confidence that our code does what we think it does. For the
future, they allow us to make changes with confidence that we are only changing
what we think we are changing in the way we expect it to change.
Communication comes in many forms. The most important is feedback, which I'll
discuss later. Another benefit of tests in general and BDD specs in particular
is that they can be used as living documentation.
Teams relax and develop trust
Customers learn to look forward to releases
Shortens feedback loop
For all you businessy types, this means shorter time to market, allows you
to leverage increased adaptibility to market transitions and promotes synergy.
Drive Development
=================
Scope Creep
-----------
Using tests to drive development allows us to maintain our focus. We only write the tests we need, and we only write enough code to make those tests pass. This helps us avoid scope creep.
Rhythm
------
Manage Change
=============
How We Test
===========
Good Tests
==========
What makes a test good? A test is good if it provides "fast focused feedback".
* Slow tests won't get run enough
* Test one thing at a time
* Localize problems quickly
* Minimize distance between test and code
Testing Smells
==============
Testing smells indicate potential design problems, but not with your tests.
These testing smells are warning you of design flaws in your code.
State Leak
----------
Long Setup Code
---------------
Indicates that your code under test is too complicated. Your classes are too
big and/or their interactions are too many.
Long Running Tests
------------------
* Won't be run often
* Haven't been run in a while
* Probably don't work
* Suggest that the code is hard to test, which is a design problem
Fragile Tests
-------------
Tests should not break unexpectedly. When they do, it suggests that your code
is interacting in surprising ways. Effects that happen at a distance are
difficult to understand and more difficult still to debug. Again, this is a
design problem, not a test problem
Testing Practices
=================
Isolation
---------
Tests should not affect one another.
Test List
---------
Regression Tests
----------------
Before you fix a bug, write a test. Then ask yourself why you didn't write that
test before you wrote the code.
Test First
----------
First Test
----------
What test should you write first? Pick a test from your list that will teach
you something and that you are confident that you can implement.
Mocking and Stubbing
--------------------
Mocking and Stubbing is a topic worthy of a few talks of its own, but I will say this:
Understand the different tools: fakes, mocks, stubs. Remember what Kent Beck
said: use the simplest thing that could possibly work.