RspecTruthTable

Provides a DSL to define a set of tests based on a truth table - for RSpec

Installation

Add this line to your application's Gemfile:

gem 'rspec_truth_table'

And then execute:

$ bundle

Or install it yourself as:

$ gem install rspec_truth_table

Usage

Include the truth_table helpers in RSpec Config

RSpec.configure do |config|
  config.extend RspecTruthTable::Helpers
end

Define a subject

describe "boolean_method" do
  subject { boolean_method(x, y, z) }

end

use the truth_table helper in your describe / context block.

describe "boolean_method" do
  subject { boolean_method(x, y, z) }

  truth_table do

  end
end

Inside the truth_table block, use the setup method to define a block that sets up the state of the test. Any arguments you specify to setup will be available to any let or before methods used inside it, these will be either true or false when the test is run. You can then use them to optionally factory an object or do other initialization steps.

describe "boolean_method" do
  subject { boolean_method(x, y, z) }

  truth_table do
    setup do |x, y, z|
       let(:x) { x }
       let(:y) { y }
       let(:z) { z }
    end
  end
end

Outside of the setup block, define a truth table with inputs and outputs. This table will have one column more than the number of inputs, as the final column specifies the expected result of the subject.

describe "boolean_method" do
  subject { boolean_method(x, y, z) }

  truth_table do
    setup do |x, y, z|
       let(:x) { x }
       let(:y) { y }
       let(:z) { z }
    end

  # X | Y | Z | R
  # -------------
    t | t | t | f
    t | t | f | f
    t | f | t | t
    t | f | f | f
    f | t | t | t
    f | t | f | f
    f | f | t | f
    f | f | f | f
  end

end

You can also use x as a wild card input, this will define tests for true and false and can aid in defining intent greatly. The following example performs the same test as above.

describe "boolean_method" do
  subject { boolean_method(x, y, z) }

  truth_table do
    setup do |x, y, z|
       let(:x) { x }
       let(:y) { y }
       let(:z) { z }
    end

    # X | Y | Z | R
    # -------------
      x | x | f | f # always false if Z is false
      t | t | x | f # X ^ Y
      f | f | x | f # X ^ Y

      x | x | x | t # The rest should result in true
  end
end

Contributing

1. Fork it ( http://github.com/thefrontiergroup/rspec_truth_table/fork )
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create new Pull Request