require 'spec_helper'
require 'combinatorics/permute'

describe Combinatorics::Permute do
  describe "cardinality" do
    it "should raise RangeError if n is negative without passing r" do
      expect { subject.cardinality(-1) }.to raise_error(RangeError)
    end

    it "should raise RangeError if n is negative when r is provided" do
      expect { subject.cardinality(-1, 1) }.to raise_error(RangeError)
    end

    it "should raise RangeError if r is negative" do
      expect { subject.cardinality(1, -1) }.to raise_error(RangeError)
    end

    it "should raise RangeError if r is greater than n" do
      expect { subject.cardinality(2, 3) }.to raise_error(RangeError)
    end

    it "should return 1 for subject.cardinality(0)" do
      expect(subject.cardinality(0)).to eq(1)
    end

    it "should return 1 for subject.cardinality(1)" do
      expect(subject.cardinality(1)).to eq(1)
    end

    it "should return 2 for subject.cardinality(2)" do
      expect(subject.cardinality(2)).to eq(2)
    end

    it "should return 6 for subject.cardinality(3)" do
      expect(subject.cardinality(3)).to eq(6)
    end

    it "should return 24 for subject.cardinality(4)" do
      expect(subject.cardinality(4)).to eq(24)
    end

    it "should return 0 for subject.cardinality(1, 0)" do
      expect(subject.cardinality(1, 0)).to eq(0)
    end

    it "should return 1 for subject.cardinality(1, 1)" do
      expect(subject.cardinality(1, 1)).to eq(1)
    end

    it "should return 2 for subject.cardinality(2, 1)" do
      expect(subject.cardinality(2, 1)).to eq(2)
    end

    it "should return 1 for subject.cardinality(2, 2)" do
      expect(subject.cardinality(2, 2)).to eq(2)
    end

    it "should return 3 for subject.cardinality(3, 1)" do
      expect(subject.cardinality(3, 1)).to eq(3)
    end

    it "should return 3 for subject.cardinality(3, 2)" do
      expect(subject.cardinality(3, 2)).to eq(6)
    end

    it "should return 1 for subject.cardinality(3, 3)" do
      expect(subject.cardinality(3, 3)).to eq(6)
    end

    it "should return 4 for subject.cardinality(4, 1)" do
      expect(subject.cardinality(4, 1)).to eq(4)
    end

    it "should return 12 for subject.cardinality(4, 2)" do
      expect(subject.cardinality(4, 2)).to eq(12)
    end

    it "should return 24 for subject.cardinality(4, 3)" do
      expect(subject.cardinality(4, 3)).to eq(24)
    end

    it "should return 1 for subject.cardinality(4, 4)" do
      expect(subject.cardinality(4, 4)).to eq(24)
    end

    it "should return 360 for subject.cardinality(6, 4)" do
      expect(subject.cardinality(6, 4)).to eq(360)
    end

    it "should return 3628800 for subject.cardinality(10)" do
      expect(subject.cardinality(10)).to eq(3628800)
    end
  end

  describe "cardinality_all" do
    it "should return [] for cardinality_all(0)" do
      expect(subject.cardinality_all(0)).to be_empty
    end

    it "should return [1] for cardinality_all(1)" do
      expect(subject.cardinality_all(1)).to eq([1])
    end

    it "should return [2, 1] for cardinality_all(2)" do
      expect(subject.cardinality_all(2)).to eq([2, 2])
    end

    it "should return [3, 6, 1] for cardinality_all(3)" do
      expect(subject.cardinality_all(3)).to eq([3, 6, 6])
    end

    it "should return [4, 12, 24, 1] for cardinality_all(4)" do
      expect(subject.cardinality_all(4)).to eq([4, 12, 24, 24])
    end

    it "should raise RangeError for cardinality_all(-1)" do
      expect { subject.cardinality_all(-1) }.to raise_error(RangeError)
    end

    it "should wrap cardinality with Permute.N" do
      should respond_to(:N)
    end

    it "should wrap cardinalith with Permute.R" do
      should respond_to(:R)
    end

    it "should wrap cardinality with Permute.NR" do
      should respond_to(:NR)
    end

    it "should alias cardinality_all to N_all" do
      should respond_to(:N_all)
    end

    it "should alias cardinality_all to NR_all" do
      should respond_to(:NR_all)
    end

    it "should alias cardinality_all to R_all" do
      should respond_to(:R_all)
    end
  end
end