Implement EmailBlackList (#5109)

* Implement BlacklistedEmailDomain

* Use Faker::Internet.domain_name

* Remove note column

* Add frozen_string_literal comment

* Delete unnecessary codes

* Sort alphabetically

* Change of wording

* Rename BlacklistedEmailDomain to EmailDomainBlock

spec/controllers/admin/email_domain_blocks_controller_spec.rb

@@ -0,0 +1,59 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe Admin::EmailDomainBlocksController, type: :controller do
+  render_views
+
+  before do
+    sign_in Fabricate(:user, admin: true), scope: :user
+  end
+
+  describe 'GET #index' do
+    around do |example|
+      default_per_page = EmailDomainBlock.default_per_page
+      EmailDomainBlock.paginates_per 1
+      example.run
+      EmailDomainBlock.paginates_per default_per_page
+    end
+
+    it 'renders email blacks' do
+      2.times { Fabricate(:email_domain_block) }
+
+      get :index, params: { page: 2 }
+
+      assigned = assigns(:email_domain_blocks)
+      expect(assigned.count).to eq 1
+      expect(assigned.klass).to be EmailDomainBlock
+      expect(response).to have_http_status(:success)
+    end
+  end
+
+  describe 'GET #new' do
+    it 'assigns a new email black' do
+      get :new
+
+      expect(assigns(:email_domain_block)).to be_instance_of(EmailDomainBlock)
+      expect(response).to have_http_status(:success)
+    end
+  end
+
+  describe 'POST #create' do
+    it 'blocks the domain when succeeded to save' do
+      post :create, params: { email_domain_block: { domain: 'example.com'} }
+
+      expect(flash[:notice]).to eq I18n.t('admin.email_domain_blocks.created_msg')
+      expect(response).to redirect_to(admin_email_domain_blocks_path)
+    end
+  end
+
+  describe 'DELETE #destroy' do
+    it 'unblocks the domain' do
+      email_domain_block = Fabricate(:email_domain_block)
+      delete :destroy, params: { id: email_domain_block.id } 
+
+      expect(flash[:notice]).to eq I18n.t('admin.email_domain_blocks.destroyed_msg')
+      expect(response).to redirect_to(admin_email_domain_blocks_path)
+    end
+  end
+end