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require File.expand_path('../../../spec_helper', __FILE__)
describe "Array#repeated_permutation" do
before :each do
@numbers = [10, 11, 12]
@permutations = [[10, 10], [10, 11], [10, 12], [11, 10], [11, 11], [11, 12], [12, 10], [12, 11], [12, 12]]
end
it "returns an Enumerator of all repeated permutations of given length when called without a block" do
enum = @numbers.repeated_permutation(2)
enum.should be_an_instance_of(Enumerator)
enum.to_a.sort.should == @permutations
end
it "yields all repeated_permutations to the block then returns self when called with block but no arguments" do
yielded = []
@numbers.repeated_permutation(2) {|n| yielded << n}.should equal(@numbers)
yielded.sort.should == @permutations
end
it "yields the empty repeated_permutation ([[]]) when the given length is 0" do
@numbers.repeated_permutation(0).to_a.should == [[]]
[].repeated_permutation(0).to_a.should == [[]]
end
it "does not yield when called on an empty Array with a nonzero argument" do
[].repeated_permutation(10).to_a.should == []
end
it "handles duplicate elements correctly" do
@numbers[-1] = 10
@numbers.repeated_permutation(2).sort.should ==
[[10, 10], [10, 10], [10, 10], [10, 10], [10, 11], [10, 11], [11, 10], [11, 10], [11, 11]]
end
it "truncates Float arguments" do
@numbers.repeated_permutation(3.7).to_a.sort.should ==
@numbers.repeated_permutation(3).to_a.sort
end
it "returns an Enumerator which works as expected even when the array was modified" do
@numbers.shift
enum = @numbers.repeated_permutation(2)
@numbers.unshift 10
enum.to_a.sort.should == @permutations
end
it "allows permutations larger than the number of elements" do
[1,2].repeated_permutation(3).sort.should ==
[[1, 1, 1], [1, 1, 2], [1, 2, 1],
[1, 2, 2], [2, 1, 1], [2, 1, 2],
[2, 2, 1], [2, 2, 2]]
end
it "generates from a defensive copy, ignoring mutations" do
accum = []
ary = [1,2]
ary.repeated_permutation(3) do |x|
accum << x
ary[0] = 5
end
accum.sort.should ==
[[1, 1, 1], [1, 1, 2], [1, 2, 1],
[1, 2, 2], [2, 1, 1], [2, 1, 2],
[2, 2, 1], [2, 2, 2]]
end
describe "when no block is given" do
describe "returned Enumerator" do
describe "size" do
it "returns 0 when combination_size is < 0" do
@numbers.repeated_permutation(-1).size.should == 0
[].repeated_permutation(-1).size.should == 0
end
it "returns array size ** combination_size" do
@numbers.repeated_permutation(4).size.should == 81
@numbers.repeated_permutation(3).size.should == 27
@numbers.repeated_permutation(2).size.should == 9
@numbers.repeated_permutation(1).size.should == 3
@numbers.repeated_permutation(0).size.should == 1
[].repeated_permutation(4).size.should == 0
[].repeated_permutation(3).size.should == 0
[].repeated_permutation(2).size.should == 0
[].repeated_permutation(1).size.should == 0
[].repeated_permutation(0).size.should == 1
end
end
end
end
end
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