drop_spec.rb

# -*- encoding: us-ascii -*-

require_relative '../../../spec_helper'
require_relative 'fixtures/classes'
require_relative '../../enumerable/shared/value_packing'
require_relative 'shared/packed_propagation'

describe "Enumerator::Lazy#drop" do
  describe "value packing of source yields (matches Enumerable#drop)" do
    before :each do
      @take = -> e { e.lazy.drop(0) }
    end
    it_behaves_like :enumerable_value_packing, nil
  end

  before :each do
    @yieldsmixed = EnumeratorLazySpecs::YieldsMixed.new.to_enum.lazy
    @eventsmixed = EnumeratorLazySpecs::EventsMixed.new.to_enum.lazy
    ScratchPad.record []
  end

  after :each do
    ScratchPad.clear
  end

  it "returns a new instance of Enumerator::Lazy" do
    ret = @yieldsmixed.drop(1)
    ret.should.instance_of?(Enumerator::Lazy)
    ret.should_not.equal?(@yieldsmixed)
  end

  it "sets difference of given count with old size to new size" do
    Enumerator::Lazy.new(Object.new, 100) {}.drop(20).size.should == 80
    Enumerator::Lazy.new(Object.new, 100) {}.drop(200).size.should == 0
  end

  describe "when the returned lazy enumerator is evaluated by Enumerable#first" do
    it "stops after specified times" do
      (0..Float::INFINITY).lazy.drop(2).first(2).should == [2, 3]

      @eventsmixed.drop(0).first(1)
      ScratchPad.recorded.should == [:before_yield]
    end
  end

  describe "when the returned lazy enumerator is evaluated by .force" do
    it "return same value when called twice" do
      lazy = [0, 1].lazy.drop(1)
      lazy.force.should == [1]
      lazy.force.should == [1]
    end
  end

  describe "on a nested Lazy" do
    it "sets difference of given count with old size to new size" do
      Enumerator::Lazy.new(Object.new, 100) {}.drop(20).drop(50).size.should == 30
      Enumerator::Lazy.new(Object.new, 100) {}.drop(50).drop(20).size.should == 30
    end

    describe "when the returned lazy enumerator is evaluated by Enumerable#first" do
      it "stops after specified times" do
        (0..Float::INFINITY).lazy.drop(2).drop(2).first(2).should == [4, 5]

        @eventsmixed.drop(0).drop(0).first(1)
        ScratchPad.recorded.should == [:before_yield]
      end
    end
  end

  it "works with an infinite enumerable" do
    s = 0..Float::INFINITY
    s.lazy.drop(100).first(100).should ==
      s.first(200).drop(100)
  end
end

describe "Enumerator::Lazy#drop" do
  describe "propagating the source yield arity to a later stage" do
    before :each do
      @stage = -> e { e.drop(0) }
    end
    it_behaves_like :enumerator_lazy_packed_propagation, nil
  end
end