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assert("Enumerator::Lazy") do
a = [1, 2]
assert_equal Enumerator::Lazy, a.lazy.class
end
assert("Enumerator::Lazy laziness") do
a = Object.new
def a.each
return to_enum :each unless block_given?
self.b << 10
yield 1
self.b << 20
yield 2
self.b << 30
yield 3
self.b << 40
yield 4
self.b << 50
yield 5
end
def a.b(b=nil)
@b = b if b
@b
end
a.b([])
assert_equal [1,2], a.each.lazy.take(2).force
assert_equal [10,20], a.b
a.b([])
assert_equal [2,4], a.each.lazy.select{|x|x%2==0}.take(2).force
assert_equal [10,20,30,40], a.b
a.b([])
assert_equal [1], a.each.lazy.take_while{|x|x<2}.take(1).force
assert_equal [10], a.b
a.b([])
assert_equal [1], a.each.lazy.take_while{|x|x<2}.take(4).force
assert_equal [10,20], a.b
end
assert("Enumrator::Lazy#to_enum") do
lazy_enum = (0..Float::INFINITY).lazy.to_enum(:each_slice, 2)
assert_kind_of Enumerator::Lazy, lazy_enum
assert_equal [0*1, 2*3, 4*5, 6*7], lazy_enum.map { |a| a.first * a.last }.first(4)
end
assert("Enumerator::Lazy#zip with cycle") do
e1 = [1, 2, 3].cycle
e2 = [:a, :b].cycle
assert_equal [[1,:a],[2,:b],[3,:a]], e1.lazy.zip(e2).first(3)
end
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