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require "spec_helper"
require "hamster/list"
describe Hamster::List do
describe "#take_while" do
it "is lazy" do
-> { Hamster.stream { fail }.take_while { false } }.should_not raise_error
end
[
[[], []],
[["A"], ["A"]],
[%w[A B C], %w[A B]],
].each do |values, expected|
context "on #{values.inspect}" do
let(:list) { L[*values] }
context "with a block" do
it "returns #{expected.inspect}" do
list.take_while { |item| item < "C" }.should eql(L[*expected])
end
it "preserves the original" do
list.take_while { |item| item < "C" }
list.should eql(L[*values])
end
it "is lazy" do
count = 0
list.take_while do |item|
count += 1
true
end
count.should <= 1
end
end
context "without a block" do
it "returns an Enumerator" do
list.take_while.class.should be(Enumerator)
list.take_while.each { |item| item < "C" }.should eql(L[*expected])
end
end
end
end
end
end
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