abc

option_test.rb

# typed: true

require "minitest/autorun"
require_relative "../lib/option"

class TestOption < Minitest::Test
  extend T::Sig

  def test_unwrap_on_some
    o = Option.some("value")
    assert_equal o.unwrap, "value"
  end

  def test_unwrap_on_none
    o = Option.none
    error = assert_raises(Option::UnwrapError) {
      o.unwrap
    }

    assert_equal error.message, "called `Option::unwrap` on a None"
  end

  def test_map_on_some
    o = Option.some("foo")
    o = o.map { |v| v + "bar" }

    assert_equal o.unwrap, "foobar"
  end

  def test_map_on_none
    o = Option.none
    o.map { |v| raise "should never be called" }

    error = assert_raises(Option::UnwrapError) {
      o.unwrap
    }

    assert_equal error.message, "called `Option::unwrap` on a None"
  end

  def test_flat_map_on_some
    o = Option.some("foo")
    o = o.flat_map { |v| Option.some(v + "bar") }

    assert_equal o.unwrap, "foobar"
  end

  def test_flat_map_on_none
    o = Option.none
    o.flat_map { |v| raise "should never be called" }

    error = assert_raises(Option::UnwrapError) {
      o.unwrap
    }

    assert_equal error.message, "called `Option::unwrap` on a None"
  end

  def test_ok_or_success
    o = Option.some("value")
    r = o.ok_or("shouldn't be used")

    assert_equal r.unwrap, "value"
  end

  def test_ok_or_failure
    o = Option.none
    r = o.ok_or("oh no")

    err = assert_raises(Result::UnwrapError) {
      r.unwrap
    }

    assert_equal err.message, "called `Result::unwrap` on a Failure containing: 'oh no'"  end

  def test_real_world_scenario
    email_address = "williammartin@github.com"

    parse_email_address(email_address)
      .flat_map { |e| lookup_user_id(e) }
  end

  sig { params(unparsed_email: String).returns(Option[String]) }
  def parse_email_address(unparsed_email)
    if !unparsed_email.include?("@")
      Option.none
    else
      Option.some(unparsed_email)
    end
  end

  sig { params(parsed_email: String).returns(Option[Integer]) }
  def lookup_user_id(parsed_email)
    if parsed_email != "williammartin@github.com"
      Option.none
    else
      Option.some(1)
    end
  end
end