Ruby developers urged to use test-driven development

Testing will help the Ruby language avoid the ill fate of Smalltalk, executive says

Paul Krill (InfoWorld)
08 May, 2009 07:53
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For the Ruby language to avoid the same ill fate as Smalltalk, developers must use test-driven development to keep code clean, an industry executive stressed Wednesday evening at the RailsConf 2009 event in Las Vegas.

Once a trendy language, Smalltalk has faded, said Robert Martin, president and CEO at Object Mentor, in a keynote presentation. He noted the language had been used in impressive projects such as a digital oscilloscope at Tektronix.

Smalltalk had been considered the language to watch from the late-1970s through to the 1990s, Martin said. "Smalltalk in its time was at the forefront of object-oriented design. Why did Smalltalk suddenly, pretty suddenly, just stop? It's certainly not alive now. No one is contemplating major projects in Smalltalk any longer," he said.

Martin said programming pioneer Ward Cunningham, inventor of such technologies as the wiki, once was asked what happened to Smalltalk and Cunningham responded that it was just too easy to make a mess of Smalltalk programming.

It is also possible to make a mess in Ruby, Martin warned. He advised the use of test-driven development as a solution.

"Test-driven development is a discipline that has permeated the Ruby and Rails community far more than any other community, I believe," Martin said. Ruby is sort of a reincarnation of Smalltalk, Martin said. "Much of the style of Ruby is similar in many ways to the style of Smalltalk," with a bit of C-like syntax, he said.

Martin advised developers to use three "laws" of test-driven development:

Do not write any production code until a "failing" unit test is written. This unit test fails because developers have not yet written the code to make it pass, Martin later explained. The test will call functions not yet written; developers then must write the functions.
Do not write more of a unit test than what is sufficient to fail.
Do not write more production code than what is sufficient to pass the failing test.

"The tests allow you to make changes without the risk of breaking something," Martin said. Developers want code to be flexible and maintainable, but nothing makes a system more flexible than a suite of tests, he said.

"Test-driven development will keep your code clean," Martin stressed. Smalltalk had been the birthplace of test-driven development, he said.