undefined method `disallow_value' for #<RSpec::Core::ExampleGroup::Nested_1:0x0000000a4b3a98>

I have the following Rspec statement:

it "requires a valid email address" do
  should disallow_value("@email.com", "email.com", "my@email",
    "my@e_mail.com", "[email protected]", "my @email.com").for(:email)
end

When I run my tests, this statement always fails with:

Failure/Error: should disallow_value("@email.com", "email.com", "my@email",
NoMethodError:
   undefined method `disallow_value' for #<RSpec::Core::ExampleGroup::Nested_1:0x000000090ea4a8>

My Shoulda versions are:

shoulda (3.5.0)
shoulda-context (1.1.6)
shoulda-matchers (2.4.0)

Any idea what's going wrong?

UPDATE:

Gemfile:

group :development, :test do
  gem 'rspec-rails'
  gem 'factory_girl_rails'
end

group :test do
  gem 'shoulda-matchers'
end

Solution

This is interesting. The README file was rewritten in November 2013 to include documentation for disallow_value, but despite a DisallowValueMatcher module devoted to implementing such a matcher, the spec for it doesn't include any use of the disallow_value method. I submitted an issue against the shoulda-matchers gem

Pending more information on this, I'd recommend using should_not allow_value as an alternative.

Update: This has been acknowledged as an error in the documentation by the shoulda gem maintainers.