Reproduction of the issue with using the `primitive` method within the custom attribute class body.

reproduction.rb

# ruby reproduction.rb

begin
  require 'bundler/inline'
rescue LoadError => e
  $stderr.puts 'Bundler version 1.10 or later is required. Please update your Bundler'
  raise e
end

gemfile(true) do
  source 'https://rubygems.org'
  gem 'virtus', '1.0.5'
  gem 'minitest', '5.9.0', require: false
end

require 'virtus'
require 'minitest/autorun'

class FiveLetterString < Virtus::Attribute
  primitive String

  def primitive
    options[:primitive]
  end

  def coerce(value)
    if value.respond_to? :to_str
      value.to_str[0..4]
    else
      value
    end
  end

  def value_coerced?(value)
    value.instance_of?(String)
  end
end

class Foo
  include Virtus.value_object

  values do
    attribute :foo, FiveLetterString
  end
end

class Bar
  include Virtus.value_object

  values do
    attribute :bar, String
  end
end

class StrictFoo
  include Virtus.value_object

  values do
    attribute :foo, FiveLetterString, strict: true
  end
end

class Bug < Minitest::Test
  def test_custom_coercion
    foo = Foo.new(foo: 'Lorem ipsum dolor sit amet')

    assert_equal 'Lorem', foo.foo
  end

  def test_correct_use_of_string_type
    bar = Bar.new(bar: 'Lorem ipsum dolor sit amet')

    assert_equal 'Lorem ipsum dolor sit amet', bar.bar
  end

  def test_custom_coercion_works_with_strict_mode
    assert_raises Virtus::CoercionError do
      StrictFoo.new(foo: nil)
    end
  end
end

test_results

Run options: --seed 12674

# Running:

F..

Finished in 0.001724s, 1739.7124 runs/s, 1739.7124 assertions/s.

  1) Failure:
Bug#test_correct_use_of_string_type [reproduction.rb:71]:
Expected: "Lorem ipsum dolor sit amet"
  Actual: "Lorem"

3 runs, 3 assertions, 1 failures, 0 errors, 0 skips