Method: Propr::RSpecAdapter#shrink

Defined in:
lib/propr/rspec.rb

#shrink(counterex) ⇒ Object

TODO: this method is not RSpec specific



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# File 'lib/propr/rspec.rb', line 50

def shrink(counterex)
  if @property.arity.zero?
    return []
  end

  xs = [counterex]

  while true
    # Generate simpler examples
    ys = Array.bind(xs) do |args|
      head, *tail = args.map{|x| x.respond_to?(:shrink) ? x.shrink : [x] }
      head.product(*tail)
    end

    zs = []

    # Collect counter examples
    until ys.empty? or zs.length >= 10
      args = ys.delete_at(rand(ys.size))

      unless @property.call(*args)
        zs.push(args)
      end
    end

    if zs.empty?
      # No simpler counter examples
      return xs.first
    else
      # Try to further simplify these
      xs = zs
    end
  end
end