mynyml.rb

While preparing to present Watchr at CUSEC’s DemoCamp, I’ve come accross this research paper about continuous testing. From the research:

“Participants using continuous testing were three times as likely to complete the task before the deadline. Participants using continuous compilation were twice as likely to complete the task, providing empirical support to a common feature in modern development environments. Most participants found continuous testing to be useful and believed that it helped them write better code faster, and 90% would recommend the tool to others. The participants did not find the tool distracting, and intuitively developed ways of incorporating the feedback into their workflow.”

Autotest <3

Like lots of rubyists, I love agile development, BDD/TDD and continuous
testing. And one of my favourite pieces of software for that task is Autotest. Whenever I start a new project, the first thing I do is open up a test file, write a placeholder test case, and fire up autotest. It’s the one gem I use on every single application I write; from gems to rails apps to bare bones rack apps, it’s always there to make my development much more enjoyable.

Well, almost always.

Some time ago I was working on a gem where I wanted to use the Expectations test framework. Expectations is not based on test/unit (as opposed to context or contest, for instance). But Autotest, by default, requires test/unit. The result wasn’t great.

Not too long ago, I was getting excited about rip, an alternative ruby package manager. So I tried using it. But autotest automatically requires rubygems. Not so compatible.

Not too long ago I started working on a webapp that has regular MRI based tests alongside JRuby based tests. But Autotest automatically ran the test suite with /usr/bin/ruby1.8. That just plain won’t work.

Watchr

“Hi. I’m Martin …. and I’m a continuous testing addict”

I was beginning to feel the withdrawal symptoms. So I started working on a solution that would satisfy my cravings in any dev environment. The result is Watchr, a continuous testing tool similar to autotest, but with a different philosophy.

Watchr aims to be much more flexible, at the cost of a few lines of setup. That is, it will read a small script file and run tests accordingly. The script file uses a very simple ruby DSL. Very simple as in a single method, that’s all it needs.

#           pattern                   action
watch('test/test_.*\.rb') {|md| system "ruby #{md[0]}"}

This tells watchr to monitor all test files (in this case all ruby files in the test/ directory that start with “test_”), and when one of those is saved, runs it with ruby. A continuous testing script for a basic project could be

watch('test/test_.*\.rb') {|md| system "ruby #{md[0]}"}
watch('lib/(.*)\.rb')     {|md| system "ruby test/test_#{md[1]}.rb"}

which, in addition to running any saved test file as above, will also run a lib file’s associated test. This mimics the equivalent autotest behaviour.

The command follows the structure:

watch('pattern') {|match_data_object| command_to_run }

Leaving the action user defined is the key. You can run JRuby-based tests, use rip, write your test suite with alternative testing frameworks, … or any combination of these.

For a good example of actual scripts, be sure to check out watchr’s own specs.watchr and docs.watchr scripts.

Install:

gem install watchr --source=http://gemcutter.org

Run:

$ cd to/your/project/root
$ watchr path/to/script

Links

source: http://github.com/mynyml/watchr
wiki: http://wiki.github.com/mynyml/watchr
bug tracker: http://github.com/mynyml/watchr/issues