Ensure registration controller block yields happen on failure in addition to success and closes #2936.

Now with 100% more unit tests.

test/controllers/custom_registrations_controller_test.rb

@@ -0,0 +1,35 @@
+require 'test_helper'
+
+class CustomRegistrationsControllerTest < ActionController::TestCase
+  tests Custom::RegistrationsController
+
+  include Devise::TestHelpers
+
+  setup do
+    request.env["devise.mapping"] = Devise.mappings[:user]
+    @password = 'password'
+    @user = create_user(password: @password, password_confirmation: @password).tap(&:confirm!)
+  end
+
+  test "yield resource to block on create success" do
+    post :create, {user: {:email => "user@example.org", :password => "password", :password_confirmation => "password"}}
+    assert @controller.create_block_called?, "create failed to yield resource to provided block"
+  end
+
+  test "yield resource to block on create failure" do
+    post :create, {user: {}}
+    assert @controller.create_block_called?, "create failed to yield resource to provided block"
+  end
+
+  test "yield resource to block on update success" do
+    sign_in @user
+    put :update, {user: {current_password: @password}}
+    assert @controller.update_block_called?, "update failed to yield resource to provided block"
+  end
+
+  test "yield resource to block on update failure" do
+    sign_in @user
+    put :update, {user: {}}
+    assert @controller.update_block_called?, "update failed to yield resource to provided block"
+  end
+end