Integrating Unit Tests In Ruby Scripts

When I write ruby scripts I like to use a single file, containing the program and all unit tests. It took me some time to find out how to add a command line switch to my ruby scripts that makes them run in script mode with full access to the Test::Unit command line arguments, while being able to run the script without the test framework interfering in the execution:

#!/usr/bin/ruby -w
require 'test/unit'

if ARGV.include?("--test")
  ARGV.delete_at(ARGV.index("--test"))
else
  Test::Unit::run = true
  puts "Running..."
end

Now you can simply run the program by typing

$ ./testme.rb
Running...

or run the tests with

$ ./testme.rb --test
Loaded suite ./testme
Started

Finished in 0.0 seconds.

0 tests, 0 assertions, 0 failures, 0 errors

The nice thing is that only the first "--test" will be removed, so you can still leverage the Test::Unit command line argument interface.