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require 'spec_helper'
describe Immutable::List do
describe '#take_while' do
it 'is lazy' do
-> { Immutable.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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