October 2003

Regular Expressions: Fit makes for good tests

by Cameron Laird and Kathryn Soraiz

Fit is a clever testing framework Ward Cunningham invented to support the acceptance tests that Extreme Programming (XP) needs. Cunningham also invented the WikiWikiWeb, or Wiki, among many other projects.

XP is a development "methodology", "a deliberate and disciplined approach" that, in the case of XP, "emphasizes customer involvement and promotes team work" through "its simple rules and practices". XP is a frequent topic for UnixReview.com articles, including such recent book reviews as Extreme Programming.

A particular focus of XP is testing. XP requires testing, of all kinds, from the first day of a development project. Among other things, this makes XP's success unusually dependent on the cost and results of testing tasks; if testing is expensive or fragile, XP loses any advantages it has.

Practical testing

That logic is a prominent part of XP's background, in fact. XP advocates generally have a lot to say about how testing isn't as tedious or impractical as many programmers seem to believe.

Figure 1

Fit demonstrates that. As Cunningham writes, Fit "is about tests that people can read", such as the example reproduced in Figure 1.