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# frozen_string_literal: true
module Pbt
module Arbitrary
# Generates arrays of values generated by `value_arb` with type `T`.
class ArrayArbitrary < Arbitrary
DEFAULT_MAX_SIZE = 10
private_constant :DEFAULT_MAX_SIZE
# @param value_arb [Arbitrary] Arbitrary to generate values.
# @param min_length [Integer] Minimum length of the generated array. Default is 0.
# @param max_length [Integer] Maximum length of the generated array. Default is 10.
def initialize(value_arb, min_length = 0, max_length = DEFAULT_MAX_SIZE)
raise ArgumentError, "min_length must be zero or positive number" if min_length < 0
@min_length = min_length
@max_length = max_length
@value_arb = value_arb
@length_arb = IntegerArbitrary.new(min_length, max_length)
end
# @see Arbitrary#generate
def generate(rng)
length = @length_arb.generate(rng)
length.times.map { @value_arb.generate(rng) }
end
# @see Arbitrary#shrink
def shrink(current)
return Enumerator.new { |_| } if current.size == @min_length
Enumerator.new do |y|
# First, shrink the length of the array and try combinations of elements.
# But this doesn't try all possible combinations since it'd be too huge and slow.
@length_arb.shrink(current.size).each do |length|
if length == 0
y.yield []
next
end
current.each_cons(length) do |con|
y.yield con
end
end
# Second, shrink each element of the array.
current.each_with_index do |item, i|
@value_arb.shrink(item).each do |val|
y.yield [*current[...i], val, *current[i + 1..]]
end
end
end
end
end
end
end
Version data entries
6 entries across 6 versions & 1 rubygems