• Distinguish Specifications from Examples: Clear separation between what is expected (specifications) and how it's demonstrated (examples).
• Logic-Free Specification Documents: Create specifications that are straightforward and free of complex logic, focusing purely on defining expected behaviors.
• Nuanced Semantic Language in Specifications: Utilize a rich, nuanced semantic language, similar to that in RFC 2119, employing keywords like MUST, SHOULD, and MAY to define different levels of requirement in specifications.
• Fast and Individual Test Execution: Enable quick execution of tests on an individual basis, providing immediate feedback on compliance with specifications.

Add to your Gemfile:

gem "fix", ">= 1.0.0.beta9"

Then execute:

bundle install

Or install it yourself:

gem install fix --pre

Specifications for a Duck class:

# examples/duck/fix.rb

require "fix"

Fix :Duck do
  it SHOULD be_an_instance_of :Duck

  on :swims do
    it MUST be_an_instance_of :String
    it MUST eql "Swoosh..."
  end

  on :speaks do
    it MUST raise_exception NoMethodError
  end

  on :sings do
    it MAY eql "♪... ♫..."
  end
end

Implementing the Duck class:

# examples/duck/app.rb

class Duck
  def walks
    "Klop klop!"
  end

  def swims
    "Swoosh..."
  end

  def quacks
    puts "Quaaaaaack!"
  end
end

Running the test:

# examples/duck/test.rb

require_relative "app"
require_relative "fix"

Fix[:Duck].test { Duck.new }

Execute:

ruby examples/duck/test.rb

Expected output:

(irb):3 Success: expected #<Duck:0x00007fb2fa208708> to be an instance of Duck.
(irb):7 Success: expected to eq "Swoosh...".
(irb):15 NoMethodError: undefined method `sings' for #<Duck:0x00007fb2fd8371d0>.
(irb):6 Success: expected "Swoosh..." to be an instance of String.
(irb):11 Success: undefined method `speaks' for #<Duck:0x00007fb2fcc79258>.

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Fix follows Semantic Versioning 2.0.

The gem is available as open source under the terms of the MIT License.

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