advent/spec/util_spec.cr

require "./spec_helper"

describe Array do
  describe "#union" do
    it "works with no elements" do
      ([] of Set(Int32)).union.should eq(Set(Int32).new)
    end

    it "correctly performs a union" do
      [Set { 1 }, Set { 2 }, Set {1, 2, 3}].union.should eq(Set { 1,2,3})
    end
  end

  describe "#intersect" do
    expect_raises(Enumerable::EmptyError) do
      ([] of Set(Int32)).intersect
    end

    it "correctly performs an intersection" do
      [Set {1}, Set {1,2}, Set {1,2,3}].intersect.should eq(Set{1})
    end
  end

  describe "#zip_with" do
    it "performs as expected" do
      [1,2,3].zip_with([2,3,4]) { |l,r| l*r }.should eq([2,6,12])
    end
  end
end

describe Tuple do
  describe "#add" do
    it "works for pairs" do
      {1,2}.add({2,3}).should eq({3,5})
    end

    it "works for triples" do
      {1,2,3}.add({3,4,5}).should eq({4, 6, 8})
    end
  end

  describe "#neg" do
    it "works for pairs" do
      {1,2}.neg.should eq({-1,-2})
    end

    it "works for triples" do
      {1,2,3}.neg.should eq({-1, -2, -3})
    end
  end

  describe "#dot" do
    it "works for pairs" do
      {1,2}.dot({2,3}).should eq(8)
    end

    it "works for triples" do
      {1,2,3}.dot({2,3,4}).should eq(20)
    end
  end

  describe "#reduce_fraction" do
    it "works with nonzero numbers" do
      [{1, 3}, {2, 6}, {3, 9}].each(&.reduce_fraction.should eq({1,3}))
    end

    it "works when the denominator is zero" do
      # This is technically not a fraction, but it helps to have
      # consistent behavior
      {5, 0}.reduce_fraction.should eq({1,0})
    end

    it "works when the numerator is zero" do
      {0, 5}.reduce_fraction.should eq({0, 1})
    end
  end
end

describe Number do
  describe "#signum" do
    it "works properly for positive numbers" do
      [1,2,3,4,5].each(&.signum.should eq(1))
    end

    it "works properly for negative numbers" do
      [-1,-2,-3,-4].each(&.signum.should eq(-1))
    end

    it "works properly for zero" do
      0.signum.should eq(0)
    end
  end
end