Remove #reset_otp_state hook (#91)

This feature was added so enable and unconfirmed mobile
phone number to be used for OTP purposes and have that
number removed at the start or end of a new session.

However, a simpler way do this would be to simply store
the unconfirmed mobile in the #user_session.  Indeed
that is what we are now doing in 18F identity project
which uses this gem:
https://github.com/18F/identity-idp/pull/220

README.md

@@ -250,39 +250,6 @@ after them):
    bundle exec rake db:rollback STEP=3
    ```
 
-#### Executing some code after the user signs in and before they sign out
-
-In some cases, you might want to perform some action right after the user signs
-in, but before the OTP is sent, and also right before the user signs out. One
-scenario where you would need this is if you are requiring users to confirm
-their phone number first before they can receive an OTP. If they enter a wrong
-number, then sign out or close the browser before they confirm, they won't be
-able to confirm their real number. To solve this problem, we need to be able to
-reset their unconfirmed number before they sign out or sign in, and before the
-OTP code is sent.
-
-To define this action, create a `#{user.class}OtpSender` class that takes the
-current user as its parameter, and defines a `#reset_otp_state` instance method.
-For example, if your user's class is `User`, you would create a `UserOtpSender`
-class, like this:
-```ruby
-class UserOtpSender
-  def initialize(user)
-    @user = user
-  end
-
-  def reset_otp_state
-    if @user.unconfirmed_mobile.present?
-      @user.update(unconfirmed_mobile: nil)
-    end
-  end
-end
-```
-If you have different types of users in your app (for example, User and Admin),
-and you need different logic for each type of user, create a second class for
-your admin user, such as `AdminOtpSender`, with its own logic for
-`#reset_otp_state`.
-
 ### Example App
 
 [TwoFactorAuthenticationExample](https://github.com/Houdini/TwoFactorAuthenticationExample)

lib/two_factor_authentication/hooks/two_factor_authenticatable.rb

@@ -1,6 +1,4 @@
 Warden::Manager.after_authentication do |user, auth, options|
-  reset_otp_state_for(user)
-
   if auth.env["action_dispatch.cookies"]
     expected_cookie_value = "#{user.class}-#{user.id}"
     actual_cookie_value = auth.env["action_dispatch.cookies"].signed[TwoFactorAuthentication::REMEMBER_TFA_COOKIE_NAME]
@@ -13,24 +11,3 @@ Warden::Manager.after_authentication do |user, auth, options|
     end
   end
 end
-
-Warden::Manager.before_logout do |user, _auth, _options|
-  reset_otp_state_for(user)
-end
-
-def reset_otp_state_for(user)
-  klass_string = "#{user.class}OtpSender"
-  klass = class_from_string(klass_string)
-
-  return unless klass
-
-  otp_sender = klass.new(user)
-
-  otp_sender.reset_otp_state if otp_sender.respond_to?(:reset_otp_state)
-end
-
-def class_from_string(string)
-  string.constantize
-rescue NameError
-  false
-end

spec/features/two_factor_authenticatable_spec.rb

@@ -187,25 +187,14 @@ feature "User of two factor authentication" do
     let(:user) { create_user }
     let(:admin) { create_admin }
 
-    scenario 'when UserOtpSender#reset_otp_state is defined' do
+    scenario 'user signs is' do
       visit new_user_session_path
       complete_sign_in_form_for(user)
 
-      expect(user.reload.email).to eq 'updated@example.com'
-    end
-
-    scenario 'when UserOtpSender#reset_otp_state is not defined' do
-      otp_sender = instance_double(UserOtpSender)
-      allow(otp_sender).to receive(:respond_to?).with(:reset_otp_state).and_return(false)
-
-      expect(UserOtpSender).to receive(:new).with(user).and_return(otp_sender)
-      expect(otp_sender).to_not receive(:reset_otp_state)
-
-      visit new_user_session_path
-      complete_sign_in_form_for(user)
+      expect(page).to have_content('Signed in successfully.')
     end
 
-    scenario 'when AdminOtpSender is not defined' do
+    scenario 'admin signs in' do
       visit new_admin_session_path
       complete_sign_in_form_for(admin)
 
@@ -217,16 +206,15 @@ feature "User of two factor authentication" do
     let(:user) { create_user }
     let(:admin) { create_admin }
 
-    scenario 'when UserOtpSender#reset_otp_state is defined' do
+    scenario 'user signs out' do
       visit new_user_session_path
       complete_sign_in_form_for(user)
-      user.update_attributes(email: 'foo@example.com')
       visit destroy_user_session_path
 
-      expect(user.reload.email).to eq 'updated@example.com'
+      expect(page).to have_content('Signed out successfully.')
     end
 
-    scenario 'when AdminOtpSender is not defined' do
+    scenario 'admin signs out' do
       visit new_admin_session_path
       complete_sign_in_form_for(admin)
       visit destroy_admin_session_path

spec/rails_app/app/services/user_otp_sender.rb

@@ -1,9 +0,0 @@
-class UserOtpSender
-  def initialize(user)
-    @user = user
-  end
-
-  def reset_otp_state
-    @user.update_attributes(email: 'updated@example.com')
-  end
-end