Good Explanation of INVEST for User Stories

Mike Caspar, a fellow agile coach,  just forwarded me this YouTube video to Bill Wake talking about INVEST for User Stories.  I worked briefly with Bill back in 2004/2005 at Capital One where he did some excellent coaching.  I strongly recommend checking out the video!

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ANN: June Agile Software Engineering Practices

Isráfíl Consulting Services is pleased to announce our upcoming:

Agile Software Engineering Practices Courses (2 day)

Software Developers, Technical Architects and Lead Developers for teams that currently use or are intending to use Agile methods such as Scrum, Extreme Programming or OpenAgile will benefit from attending this course.
After completing this course you will:

  • increase your development productivity
  • be familiar with basic disciplines to create well-tested, defect-free code
  • be able to integrate successfully into Agile teams
  • understand what makes healthy, maintainable code
  • receive a Certificate of Attendance
  • receive $100.00 discount on a 3-day Scrum training and certification course by our partners

Available Classes:

  • 2009-06-22: 2-day Agile Software Engineering Practices – Ottawa, ON $1450.00 CAD [16 spaces]
    • Register by June 1 and get the early-bird price of $1,250.00.
  • 2009-06-25: 2-day Agile Software Engineering Practices – Markham, ON $1450.00 CAD [16 spaces]
    • Register by June 1 and get the early-bird price of $1,250.00.


Register!: http://www.israfil.net/publictraining/registerCourse Details: http://www.israfil.net/publictraining/coursesClass Schedules: http://www.israfil.net/publictraining/scheduleFor more information, please e-mail us at: training@israfil.net

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ANN: Agile Software Engineering Practices training by Isráfíl Consulting

Isráfíl Consulting is finally prepared for the first series of its Agile Software Engineering Practices training courses. This series is offered in partnership with Berteig Consulting who are graciously hosting the registration process. Their team has also helped greatly in shaping the presentation style and structure of the course. The initial run will be in Ottawa, Toronto (Markham), and Kitchener/Waterloo.   

Topics covered will include Test Driven Development (TDD), testability, supportive infrastructure such as build and continuous integration, team metrics, incremental design and evolutionary architecture, dependency injection, and so much more. (This course won’t present the planning side of XP, but covers many other aspects common to XP projects) It makes a great complement for training in Agile Processes such as XP, Scrum, or OpenAgile. The overview slide presentation is available for free download from the Isráfíl web site.

The courses are scheduled for:

The course is $1250 CAD per student, and participants receive a transferrable discount of $100 CAD for other training with Berteig Consulting as a part of our ongoing partnership. I initially prototyped this course in Ottawa this December, and am very excited to see this through in several locales. Class size is limited to 15, so we can keep the instruction style more involved. The above schedules are linked to Berteig Consulting’s course system and have registration links at the bottom of the description. Locations are TBD, but will be updated at the above links as soon as they’re finalized.

A further series is planned for several US cities in March, and we’ll be sure to announce them as well.

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Yet another misunderstanding of TDD, testing, and code coverage

I was vaguely annoyed to see this blog article featured in JavaLobby’s recent mailout. Not because Kevin Pang doesn’t make some good points about the limits of code coverage, but because his title is needlessly controversial. And, because JavaLobby is engaging in some agile-baiting by publishing it without some editorial restraint.

In asking the question, “Is code coverage all that useful,” he asserts at the beginning of his article that Test Driven Development (TDD) proponents “often tend to push code coverage as a useful metric for gauging how well tested an application is.” This statement is true, but the remainder of the blog post takes apart code coverage as a valid “one true metric,” a claim that TDD proponents don’t make, except in Kevin’s interpretation.

He further asserts that “100% code coverage has long been the ultimate goal of testing fanatics.” This isn’t true. High code coverage is a desired attribute of a well tested system, but the goal is to have a fully and sufficiently tested system. Code coverage is indicative, but not proof, of a well-tested system. How do I mean that? Any system whose authors have taken the time to sufficiently test it such that it gets > 95% code coverage is likely (in my experience) thinking through how to test their system in order to fully express its happy paths, edge cases, etc. However, the code coverage here is a symptom, not a cause, of a well-tested system. And the metric can be gamed. Actually, when imposed as a management quality criterion, it usually is gamed. Good metrics should confirm a result obtained by other means, or provide leading indicators. Few numeric measurements are subtle enough to really drive system development.

Having said that, I have used code-coverage in this way, but in context, as I’ll mention later in this post.

Kevin provides example code similar to the following:

String foo(boolean condition) {
    if (condition)
        return "true";
    else
        return "false";
}

… and talks about how if the unit tests are only testing the true path, then this is only working on 50% coverage. Good so far. But then he goes on to express that “code coverage only tells us what was executed by our unit tests, not what executed correctly.” He is carefully telling us that a unit test executing a line doesn’t guarantee that the line is working as intended. Um… that’s obvious. And if the tests didn’t pass correctly, then the line should not be considered covered. It seems there are some unclear assumptions on how testing needs to work, so let me get some assertions out of the way…

  1. Code coverage is only meaningful in the context of well-written tests. It doesn’t save you from crappy tests.
  2. Code coverage should only be measured on a line/branch if the covering tests are passing.
  3. Code coverage suggests insufficiency, but doesn’t guarantee sufficiency.
  4. Test-driven code will likely have the symptom of nearly perfect coverage.
  5. Test-driven code will be sufficiently tested, because the author wrote all the tests that form, in full, the requirements/spec of that code.
  6. Perfectly covered code will not necessarily be sufficiently tested.

What I’m driving at is that Kevin is arguing against something entirely different than that which TDD proponents argue. He’s arguing against a common misunderstanding of how TDD works. On point 1 he and I are in agreement. Many of his commentators mention #3 (and he states it in various ways himself). His description of what code coverage doesn’t give you is absurd when you take #2 into account (we assume that a line of covered code is only covered if the covering test is passing). But most importantly – “TDD proponents” would, in my experience, find this whole line of explanation rather irrelevant, as it is an argument against code-coverage as a single metric for code quality, and they would attempt to achieve code quality through thoroughness of testing by driving the development through tests. TDD is a design methodology, not a testing methodology. You just get tests as side-effect artifacts of the approach. Useful in their own right? Sure, but it’s only sort of the point. It isn’t just writing the tests-first.

In other words – TDD implies high or perfect coverage. But the inverse is not necessarily true.

How do you achieve thoroughness by driving your development with tests? You imagine the functionality you need next (your next increment of useful change), and you write or modify your tests to “require” the new piece of functionality. They you write it, then you go green. Code coverage doesn’t enter into it, because you should have near perfect coverage at all times by implication, because every new piece of functionality you develop is preceded by tests which test its main paths and error states, upper and lower bounds, etc. Code coverage in this model is a great way to notice that you screwed up and missed something, but nothing else.

So, is code-coverage useful? Heck yeah! I’ve used coverage to discover lots of waste in my system. I’ve removed whole sets of APIs that were “just in case I need them” APIs, because they become rote (lots of accessors/mutators that are not called in normal operations). Is code coverage the only way I would find them? No. If I’m dealing with a system that wasn’t driven with tests, or was poorly tested in general, I may use coverage as a quick health meter, but probably not. Going from zero to 90% on legacy code is likely to be less valuable than just re-writing whole subsystems using TDD… and often more expensive.

Regardless, while Kevin is formally asking “is code coverage useful?” he’s really asking (rhetorically) is it reasonable to worship code coverage as the primary metric. But if no one’s asserting the positive, why is he questioning it? He may be dealing with a lot of people with misunderstandings of how TDD works. He could be dealing with metrics bigots. He could be dealing with management-imposed-metrics initiatives which often fail. It might be a pet peeve or he’s annoyed with TDD and this is a great way to do some agile-baiting of his own. I don’t know him, so I can’t say. His comments seem reasonable, so I assume no ill intent. But the answer to his rhetorical question is “yes, but in context.” Not surprising, since most rhetorically asked questions are answerable in this fashion. Hopefully it’s a bit clearer where it’s useful (and where/how) it’s not.

(This article is a cross-post from “Geek in a Suit”)

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Comprehensive List of Agile Practices

This might be impossible, but I was thinking that it would be cool to have a single reference of all the possible agile practices.  Obviously, since “agile” is not a single defined method, we must take the word “comprehensive” with a bit of humor (or a grain of salt).  I’ve attached a spreadsheet that represents my first draft (it’s in OpenOffice.org format so that you don’t have to worry about me spreading viruses – if you want it in MS Office format, email me at mishkin@berteigconsulting.com).  I’ve split the practices up into several sections including: “Agile Skeleton”, “Common Practices”, “Basic Scrum Practices”, “Optional Scrum Practices”, “Extreme Programming Practices” and “Lean Practices”.  I’ve stopped there because I’m not an expert on other agile methods such as Crystal, Agile Unified Process or Feature Driven Development.  I imagine that this list will be useful for teams to do self-assessment and to think about ways they might improve.  Perhaps it could be used in a retrospective setting.  Berteig Consulting coaches use something similar to this to assess the effectiveness of their engagement with clients.  If you think of practices I’ve missed or other potential uses for a list like this, let me know in the comments.  My intention is to convert this to a wiki and make it available under a Creative Commons license once it is a little more refined.

Agile Practices List (OpenOffice format – 68KB)

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Agile Blogs

There’s a great discussion on the Extreme Programming Yahoo! group where a whole bunch of folks list their blogs out. If you aren’t part of the group, you should probably join it (it focuses on technical practices, and there’s lots of other good agile stuff there too). The discussion starts with a message from James Carr where he asks who else here blogs?

It’s probably still cool to jump in with your own blog link if you have an agile-focused blog (I’m sure Scrum, Lean and other agile methods would be welcome even though it’s an extreme programming list!)

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Excellent Article about Planning Velocity

J. B. Rainsberger has written an excellent article about the usefulness of planning velocity (and the places where it is not useful as well). I highly recommend reading it, particularly if you are a manager or a project manager.

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