OmniAuth has some facilities for mocking its authentication flow when you are performing integration tests. Here's how it works.

You can turn on "test mode" for OmniAuth like so:

OmniAuth.config.test_mode = true

Once you have enabled test mode, all requests to OmniAuth will be short circuited to use the mock authentication hash as described below. A request to /auth/provider will redirect immediately to /auth/provider/callback.

The mock_auth configuration allows you to set per-provider (or default) authentication hashes to return during integration testing. You can set it like so:

OmniAuth.config.mock_auth[:twitter] = OmniAuth::AuthHash.new({
  :provider => 'twitter',
  :uid => '123545'
  # etc.
})

You can set the :default key to return a hash for providers that haven't been specified. Once you set the mock auth hash and turn on test mode, all requests to OmniAuth will return an auth hash from the mock.

Check out faker-omniauth for an easy way to generate mock data.

You can also use the shortcut #add_mock method to quickly add a new mock provider. This information will automatically be merged with the default info so it will be a valid response.

OmniAuth.config.add_mock(:twitter, {:uid => '12345'})

If you set a provider's mock to a symbol instead of a hash, it will fail with that message.

OmniAuth.config.mock_auth[:twitter] = :invalid_credentials

You will be redirected back to /auth/failure?message=invalid_credentials.

By default Omniauth will raise an exception for invalid credentials in the development and test environments. If you'd like to be redirected to the /auth/failure endpoint in those environments, include this code:

OmniAuth.config.on_failure = Proc.new { |env|
  OmniAuth::FailureEndpoint.new(env).redirect_to_failure
}

In between tests, you probably want to reset OmniAuth to a consistent state. In your test-suite-wide configuration (e.g. in setup or before(:each)), run

OmniAuth.config.mock_auth[:twitter] = nil

When testing the OmniAuth, you need to set two environment variables, see the sample below using RSpec and Twitter OmniAuth:

before do 
  request.env["devise.mapping"] = Devise.mappings[:user] # If using Devise
  request.env["omniauth.auth"] = OmniAuth.config.mock_auth[:twitter] 
end

Or when using request specs with newer versions of RSpec, which do not allow access to the request object:

before do
  Rails.application.env_config["devise.mapping"] = Devise.mappings[:user] # If using Devise
  Rails.application.env_config["omniauth.auth"] = OmniAuth.config.mock_auth[:twitter]
end

This prevents the route error, see the sample below

Failure/Error: get :twitter
AbstractController::ActionNotFound:
  Could not find devise mapping for path "/users/auth/twitter/callback".
  Maybe you forgot to wrap your route inside the scope block? For example:
    devise_scope :user do
      match "/some/route" => "some_devise_controller"
    end