Exploration Through Example

Example-driven development, Agile testing, context-driven testing, Agile programming, Ruby, and other things of interest to Brian Marick
191.8 167.2 186.2 183.6 184.0 183.2 184.6

Fri, 21 Apr 2006

Agile definitions

No doubt because I'm a self-proclaimed skeptic about definitions, I was asked:

[...] can you supply dictionary-like definitions for:

test-driven design

example-driven design

agile methodology


My answer:

test-driven design

A style of program design that begins by writing one simple test, then writing just enough code to pass it. Then another simple test is written, and code is added to pass both it and the previous test. The programmer then looks for opportunities to improve the code by generalizing it, removing duplication, restructuring it, or making it more understandable. The test-code-improve cycle repeats until there are no more tests to be had. It is claimed that a good global design emerges from (1) the need to decouple the code to make tests run fast, and (2) the local heuristic rules for code improvement. The tests are retained and run frequently to prevent unintended effects of changes to the design.

example-driven design

A variant of test-driven design with a particular answer to the question "What test should be next?" The tests are written as if they were a series of examples being used to teach someone how to use the code, beginning with simple cases and moving toward the trickier ones.

agile methodology

A style of software development characterized by its release schedule, attitude toward change, and patterns of communication. (1) The product is developed in iterations, usually one to four weeks long. At the end of each iteration, it has additional, fully implemented business value--not just more code--and is ready to be deployed (although it may not be). (2) The design horizon usually extends only to the end of the current iteration; little code is written in anticipation of future needs. Since the project is seen by the programmers as a stream of unanticipated requirements, the team and product are forced to learn to accommodate change. There is no concept of "requirements churn" and no need for a requirements freeze. (3) Written natural language communication is considered a usually-inefficient compromise. Face-to-face communication is higher bandwidth (but transient). Executable documentation—code and tests—is permanent, less ambiguous, and self-checking (but slower to write and read). Agile projects prefer a combination of the latter two over the the first.

## Posted at 17:00 in category /agile [permalink] [top]

How to be a product director

I've finished a first draft of "How to be a Product Director." PDF, 17 pages (with pictures and screen shots and pull quotes and sidebars). Comments welcome.

Some projects call it "the Customer." Others call it "the product owner." Some call it "the goal donor." I and a few others call it the Product Director. Like a film director, the product director is the one person with the clearest vision of the final result. But—like a film director—the role isn't a passive one of "expressing the vision." It's an active role, one of pointing the work of other people in a particular direction, evaluating the results, and adjusting the direction based on the reality of what the last bout of work produced.

It's the hardest job on an Agile project.

The job revolves around four verbs: inform, observe, adjust, and represent.

The product director informs the programmers of what to do next by providing them with stories. [sidebar defining "story"] In order to estimate the cost of a story and implement it successfully, the programmers need:[...]

## Posted at 07:33 in category /agile [permalink] [top]

About Brian Marick
I consult mainly on Agile software development, with a special focus on how testing fits in.

Contact me here: marick@exampler.com.




Agile Testing Directions
Tests and examples
Technology-facing programmer support
Business-facing team support
Business-facing product critiques
Technology-facing product critiques
Testers on agile projects

Permalink to this list


Working your way out of the automated GUI testing tarpit
  1. Three ways of writing the same test
  2. A test should deduce its setup path
  3. Convert the suite one failure at a time
  4. You should be able to get to any page in one step
  5. Extract fast tests about single pages
  6. Link checking without clicking on links
  7. Workflow tests remain GUI tests
Permalink to this list


Design-Driven Test-Driven Design
Creating a test
Making it (barely) run
Views and presenters appear
Hooking up the real GUI


Popular Articles
A roadmap for testing on an agile project: When consulting on testing in Agile projects, I like to call this plan "what I'm biased toward."

Tacit knowledge: Experts often have no theory of their work. They simply perform skillfully.

Process and personality: Every article on methodology implicitly begins "Let's talk about me."


Related Weblogs

Wayne Allen
James Bach
Laurent Bossavit
William Caputo
Mike Clark
Rachel Davies
Esther Derby
Michael Feathers
Developer Testing
Chad Fowler
Martin Fowler
Alan Francis
Elisabeth Hendrickson
Grig Gheorghiu
Andy Hunt
Ben Hyde
Ron Jeffries
Jonathan Kohl
Dave Liebreich
Jeff Patton
Bret Pettichord
Hiring Johanna Rothman
Managing Johanna Rothman
Kevin Rutherford
Christian Sepulveda
James Shore
Jeff Sutherland
Pragmatic Dave Thomas
Glenn Vanderburg
Greg Vaughn
Eugene Wallingford
Jim Weirich


Where to Find Me

Software Practice Advancement


All of 2006
All of 2005
All of 2004
All of 2003



Agile Alliance Logo