rails--rails/activesupport/test/memoizable_test.rb

require 'abstract_unit'

class MemoizableTest < ActiveSupport::TestCase
  class Person
    extend ActiveSupport::Memoizable

    attr_reader :name_calls, :age_calls, :is_developer_calls

    def initialize
      @name_calls = 0
      @age_calls = 0
      @is_developer_calls = 0
    end

    def name
      @name_calls += 1
      "Josh"
    end

    def name?
      true
    end
    memoize :name?

    def update(name)
      "Joshua"
    end
    memoize :update

    def age
      @age_calls += 1
      nil
    end

    memoize :name, :age

    private

    def is_developer?
      @is_developer_calls += 1
      "Yes"
    end
    memoize :is_developer?
  end

  class Company
    attr_reader :name_calls
    def initialize
      @name_calls = 0
    end

    def name
      @name_calls += 1
      "37signals"
    end
  end

  module Rates
    extend ActiveSupport::Memoizable

    attr_reader :sales_tax_calls
    def sales_tax(price)
      @sales_tax_calls ||= 0
      @sales_tax_calls += 1
      price * 0.1025
    end
    memoize :sales_tax
  end

  class Calculator
    extend ActiveSupport::Memoizable
    include Rates

    attr_reader :fib_calls
    def initialize
      @fib_calls = 0
    end

    def fib(n)
      @fib_calls += 1

      if n == 0 || n == 1
        n
      else
        fib(n - 1) + fib(n - 2)
      end
    end
    memoize :fib

    def counter
      @count ||= 0
      @count += 1
    end
    memoize :counter
  end

  def setup
    @person = Person.new
    @calculator = Calculator.new
  end

  def test_memoization
    assert_equal "Josh", @person.name
    assert_equal 1, @person.name_calls

    3.times { assert_equal "Josh", @person.name }
    assert_equal 1, @person.name_calls
  end

  def test_memoization_with_punctuation
    assert_equal true, @person.name?

    assert_nothing_raised(NameError) do
      @person.memoize_all
      @person.unmemoize_all
    end
  end

  def test_memoization_with_nil_value
    assert_equal nil, @person.age
    assert_equal 1, @person.age_calls

    3.times { assert_equal nil, @person.age }
    assert_equal 1, @person.age_calls
  end

  def test_memorized_results_are_immutable
    # This is purely a performance enhancement that we can revisit once the rest of
    # the code is in place. Ideally, we'd be able to do memoization in a freeze-friendly
    # way without amc hacks
    pending do
      assert_equal "Josh", @person.name
      assert_raise(ActiveSupport::FrozenObjectError) { @person.name.gsub!("Josh", "Gosh") }
    end
  end

  def test_reloadable
    counter = @calculator.counter
    assert_equal 1, @calculator.counter
    assert_equal 2, @calculator.counter(:reload)
    assert_equal 2, @calculator.counter
    assert_equal 3, @calculator.counter(true)
    assert_equal 3, @calculator.counter
  end

  def test_flush_cache
    assert_equal 1, @calculator.counter

    assert @calculator.instance_variable_get(:@_memoized_counter).any?
    @calculator.flush_cache(:counter)
    assert @calculator.instance_variable_get(:@_memoized_counter).empty?

    assert_equal 2, @calculator.counter
  end

  def test_unmemoize_all
    assert_equal 1, @calculator.counter

    assert @calculator.instance_variable_get(:@_memoized_counter).any?
    @calculator.unmemoize_all
    assert @calculator.instance_variable_get(:@_memoized_counter).empty?

    assert_equal 2, @calculator.counter
  end

  def test_memoize_all
    @calculator.memoize_all
    assert @calculator.instance_variable_defined?(:@_memoized_counter)
  end

  def test_memoization_cache_is_different_for_each_instance
    assert_equal 1, @calculator.counter
    assert_equal 2, @calculator.counter(:reload)
    assert_equal 1, Calculator.new.counter
  end

  def test_memoized_is_not_affected_by_freeze
    @person.freeze
    assert_equal "Josh", @person.name
    assert_equal "Joshua", @person.update("Joshua")
  end

  def test_memoization_with_args
    assert_equal 55, @calculator.fib(10)
    assert_equal 11, @calculator.fib_calls
  end

  def test_reloadable_with_args
    assert_equal 55, @calculator.fib(10)
    assert_equal 11, @calculator.fib_calls
    assert_equal 55, @calculator.fib(10, :reload)
    assert_equal 12, @calculator.fib_calls
    assert_equal 55, @calculator.fib(10, true)
    assert_equal 13, @calculator.fib_calls
  end

  def test_object_memoization
    [Company.new, Company.new, Company.new].each do |company|
      company.extend ActiveSupport::Memoizable
      company.memoize :name

      assert_equal "37signals", company.name
      assert_equal 1, company.name_calls
      assert_equal "37signals", company.name
      assert_equal 1, company.name_calls
    end
  end

  def test_memoized_module_methods
    assert_equal 1.025, @calculator.sales_tax(10)
    assert_equal 1, @calculator.sales_tax_calls
    assert_equal 1.025, @calculator.sales_tax(10)
    assert_equal 1, @calculator.sales_tax_calls
    assert_equal 2.5625, @calculator.sales_tax(25)
    assert_equal 2, @calculator.sales_tax_calls
  end

  def test_object_memoized_module_methods
    company = Company.new
    company.extend(Rates)

    assert_equal 1.025, company.sales_tax(10)
    assert_equal 1, company.sales_tax_calls
    assert_equal 1.025, company.sales_tax(10)
    assert_equal 1, company.sales_tax_calls
    assert_equal 2.5625, company.sales_tax(25)
    assert_equal 2, company.sales_tax_calls
  end

  def test_double_memoization
    assert_raise(RuntimeError) { Person.memoize :name }
    person = Person.new
    person.extend ActiveSupport::Memoizable
    assert_raise(RuntimeError) { person.memoize :name }

    company = Company.new
    company.extend ActiveSupport::Memoizable
    company.memoize :name
    assert_raise(RuntimeError) { company.memoize :name }
  end

  def test_private_method_memoization
    person = Person.new

    assert_raise(NoMethodError) { person.is_developer? }
    assert_equal "Yes", person.send(:is_developer?)
    assert_equal 1, person.is_developer_calls
    assert_equal "Yes", person.send(:is_developer?)
    assert_equal 1, person.is_developer_calls
  end

end