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require_relative '../../spec_helper'
describe "Enumerator.produce" do
it "creates an infinite enumerator" do
enum = Enumerator.produce(0) { |prev| prev + 1 }
enum.take(5).should == [0, 1, 2, 3, 4]
end
it "terminates iteration when block raises StopIteration exception" do
enum = Enumerator.produce(0) do | prev|
raise StopIteration if prev >= 2
prev + 1
end
enum.to_a.should == [0, 1, 2]
end
context "when initial value skipped" do
it "uses nil instead" do
ScratchPad.record []
enum = Enumerator.produce { |prev| ScratchPad << prev; (prev || 0) + 1 }
enum.take(3).should == [1, 2, 3]
ScratchPad.recorded.should == [nil, 1, 2]
end
it "starts enumerable from result of first block call" do
array = "a\nb\nc\nd".lines
lines = Enumerator.produce { array.shift }.take_while { |s| s }
lines.should == ["a\n", "b\n", "c\n", "d"]
end
end
end
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