ruby--ruby/spec/ruby/library/prime/each_spec.rb

require_relative '../../spec_helper'

ruby_version_is ""..."3.1" do
  require 'prime'

  describe :prime_each, shared: true do
    before :each do
      ScratchPad.record []
    end

    it "enumerates primes" do
      primes = Prime.instance
      result = []

      primes.each { |p|
        result << p
        break if p > 10
      }

      result.should == [2, 3, 5, 7, 11]
    end

    it "yields ascending primes to the block" do
      previous = 1
      @object.each do |prime|
        break if prime > 1000
        ScratchPad << prime
        prime.should > previous
        previous = prime
      end

      all_prime = true
      ScratchPad.recorded.all? do |prime|
        all_prime &&= (2..Math.sqrt(prime)).all? { |d| prime % d != 0 }
      end

      all_prime.should be_true
    end

    it "returns the last evaluated expression in the passed block" do
      @object.each { break :value }.should equal(:value)
    end

    describe "when not passed a block" do
      before :each do
        @prime_enum = @object.each
      end

      it "returns an object that is Enumerable" do
        @prime_enum.each.should be_kind_of(Enumerable)
      end

      it "returns an object that responds to #with_index" do
        @prime_enum.should respond_to(:with_index)
      end

      it "returns an object that responds to #with_object" do
        @prime_enum.should respond_to(:with_object)
      end

      it "returns an object that responds to #next" do
        @prime_enum.should respond_to(:next)
      end

      it "returns an object that responds to #rewind" do
        @prime_enum.should respond_to(:rewind)
      end

      it "yields primes starting at 2 independent of prior enumerators" do
        @prime_enum.next.should == 2
        @prime_enum.next.should == 3

        @object.each { |prime| break prime }.should == 2
      end

      it "returns an enumerator that yields previous primes when #rewind is called" do
        @prime_enum.next.should == 2
        @prime_enum.next.should == 3
        @prime_enum.rewind
        @prime_enum.next.should == 2
      end

      it "returns independent enumerators" do
        enum = @object.each
        enum.next.should == 2
        enum.next.should == 3

        @prime_enum.next.should == 2

        enum.next.should == 5
      end
    end
  end

  describe :prime_each_with_arguments, shared: true do
    before :each do
      ScratchPad.record []
    end

    it "yields ascending primes less than or equal to the argument" do
      bound = 1000
      previous = 1
      @object.each(bound) do |prime|
        ScratchPad << prime
        prime.should > previous
        previous = prime
      end

      ScratchPad.recorded.all? do |prime|
        (2..Math.sqrt(prime)).all? { |d| prime % d != 0 }
      end.should be_true

      ScratchPad.recorded.all? { |prime| prime <= bound }.should be_true
    end

    it "returns nil when no prime is generated" do
      @object.each(1) { :value }.should be_nil
    end

    it "yields primes starting at 2 independent of prior enumeration" do
      @object.each(10) { |prime| prime }.should == 7
      @object.each(10) { |prime| break prime }.should == 2
    end

    it "accepts a pseudo-prime generator as the second argument" do
      generator = mock('very bad pseudo-prime generator')
      generator.should_receive(:upper_bound=).with(100)
      generator.should_receive(:each).and_yield(2).and_yield(3).and_yield(4)

      @object.each(100, generator) { |prime| ScratchPad << prime }
      ScratchPad.recorded.should == [2, 3, 4]
    end

    describe "when not passed a block" do
      it "returns an object that returns primes less than or equal to the bound" do
        bound = 100
        @object.each(bound).all? { |prime| prime <= bound }.should be_true
      end
    end
  end

  describe "Prime.each" do
    it_behaves_like :prime_each, :each, Prime
  end

  describe "Prime.each" do
    it_behaves_like :prime_each_with_arguments, :each, Prime
  end

  describe "Prime#each with Prime.instance" do
    it_behaves_like :prime_each, :each, Prime.instance
  end

  describe "Prime#each with Prime.instance" do
    it_behaves_like :prime_each_with_arguments, :each, Prime.instance
  end

  describe "Prime#each with Prime.instance" do
    before :each do
      @object = Prime.instance
    end

    it_behaves_like :prime_each, :each

    it "resets the enumerator with each call" do
      @object.each { |prime| break if prime > 10 }
      @object.each { |prime| break prime }.should == 2
    end
  end
end