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require File.expand_path('../../../spec_helper', __FILE__)
require File.expand_path('../fixtures/classes', __FILE__)
ruby_version_is "1.8.7" do
describe "Array#permutation" do
before(:each) do
@numbers = (1..3).to_a
@yielded = []
end
it "returns an Enumerator of all permutations when called without a block or arguments" do
enum = @numbers.permutation
enum.should be_an_instance_of(enumerator_class)
enum.to_a.sort.should == [
[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2],[3,2,1]
].sort
end
it "returns an Enumerator of permutations of given length when called with an argument but no block" do
enum = @numbers.permutation(1)
enum.should be_an_instance_of(enumerator_class)
enum.to_a.sort.should == [[1],[2],[3]]
end
it "yields all permutations to the block then returns self when called with block but no arguments" do
array = @numbers.permutation {|n| @yielded << n}
array.should be_an_instance_of(Array)
array.sort.should == @numbers.sort
@yielded.sort.should == [
[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2],[3,2,1]
].sort
end
it "yields all permutations of given length to the block then returns self when called with block and argument" do
array = @numbers.permutation(2) {|n| @yielded << n}
array.should be_an_instance_of(Array)
array.sort.should == @numbers.sort
@yielded.sort.should == [[1,2],[1,3],[2,1],[2,3],[3,1],[3,2]].sort
end
it "returns the empty permutation ([[]]) when the given length is 0" do
@numbers.permutation(0).to_a.should == [[]]
@numbers.permutation(0) { |n| @yielded << n }
@yielded.should == [[]]
end
it "returns the empty permutation([]) when called on an empty Array" do
[].permutation.to_a.should == [[]]
[].permutation { |n| @yielded << n }
@yielded.should == [[]]
end
it "returns no permutations when the given length has no permutations" do
@numbers.permutation(9).entries.size == 0
@numbers.permutation(9) { |n| @yielded << n }
@yielded.should == []
end
it "handles duplicate elements correctly" do
@numbers << 1
@numbers.permutation(2).sort.should == [
[1,1],[1,1],[1,2],[1,2],[1,3],[1,3],
[2,1],[2,1],[2,3],
[3,1],[3,1],[3,2]
].sort
end
it "handles nested Arrays correctly" do
# The ugliness is due to the order of permutations returned by
# permutation being undefined combined with #sort croaking on Arrays of
# Arrays.
@numbers << [4,5]
got = @numbers.permutation(2).to_a
expected = [
[1, 2], [1, 3], [1, [4, 5]],
[2, 1], [2, 3], [2, [4, 5]],
[3, 1], [3, 2], [3, [4, 5]],
[[4, 5], 1], [[4, 5], 2], [[4, 5], 3]
]
expected.each {|e| got.include?(e).should be_true}
got.size.should == expected.size
end
it "truncates Float arguments" do
@numbers.permutation(3.7).to_a.sort.should ==
@numbers.permutation(3).to_a.sort
end
it "returns an Enumerator which works as expected even when the array was modified" do
@numbers = [1, 2]
enum = @numbers.permutation
@numbers << 3
enum.to_a.sort.should == [
[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2],[3,2,1]
].sort
end
it "generates from a defensive copy, ignoring mutations" do
accum = []
ary = [1,2,3]
ary.permutation(3) do |x|
accum << x
ary[0] = 5
end
accum.should == [[1, 2, 3], [1, 3, 2], [2, 1, 3], [2, 3, 1], [3, 1, 2], [3, 2, 1]]
end
end
end
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