stig

Simple test input generation.

Stig is a small library for property based testing in Ruby. It runs a test multiple times (100 by default) with randomly generated input. Stig is test framework agnostic, so can be used with any test framework.

An example using cutest. test and assert_raise come from cutest.

require "stig"

test "doesn't parse random input" do
  Stig.property(String) do |string|
    assert_raise { Library.parse(string) }
  end
end

Stig.property takes one or more generators and a predicate block. A generator is an object implementing #call or #random. A predicate block is a block that returns true for passed tests and false for failed test.

Note: In the above example String is used as generator. Stig doesn't monkey-patch any core classes.

Stig ships with a few built in generators, such as Date, Integer and String. They can be found under the Stig::Generators namespace. It's easy to write your own generators using Stig.generator and Stig.generator_for.

An example of creating a custom generator using Stig.generator.

Person = Struct.new(:name, :age)

person_generator = generator do
  Person.new Generators::String.random, Generators::Integer.random(99)
end

person_generator.call
# => #<struct Person name="M#uVfd7\tx\x1Eri]\x1F\x7F", age=95>

An example of creating a custom generator using Stig.generator_for.

Person = Struct.new(:name, :age) do
  def self.random
    new Generators::String.random, Generators::Integer.random(99)
  end
end

person_generator = generator_for(Person)

person_generator.call
# => #<struct Person name="-\x069|\x0F\x03Llq", age=6>

To configure the number of tests stig should run set the environment variable STIG_NUMBER_OF_RUNS to the desired number of test runs.

gem install stig

Stig requires Ruby 1.9.3 or higher.

See the LICENSE file.