NOTES.md

Property DSL

Properties are basically just functions. They look like this:

lambda{|a,...| ... }

Property DSL

• error?(ex) { ... }
  True if code block throws an exception

• guard(cond)
  Skip test for inputs that don't meet the condition

• label(str)
  Classify each invocation of the property

Random DSL

• scale(n, zero)
  Scale the numeric value closer to zero, using current factor 0..1

• guard(cond)
  Supress the generated value unless a condition is met

• rand(limit)
  Generate a random number using Kernel.rand

Wiring

Define boolean property

>> f = lambda{|a,b,c| a + (b + c) == (a + b) + c }
=> #<Proc:...>

>> p = Propr::Property.new("assoc", Propr::Dsl::Property.new(f))
=> #<Propr::Property:...>

Define generator of random data

>> c = lambda do
     bind(Integer.random) do |a|
     bind(Integer.random) do |b|
     bind(Integer.random) do |c|
       unit([a, b, c]);
     end; end; end; end
=> #<Proc:...>

>> c = Propr::Dsl::Check.wrap(r)
=> #<Proc:...>

Generating a random input

>> Propr::Random.eval r
=> [-1473273057635678493, 3003717222078111739, -4075345202237457298]

Simple API for testing the property with random data

>> p.check { Propr::Random.eval c }
=> true