Feature/update confirmation email information (#145)

* Add `invited_by` foreign key to User

Allows for a User to be tied to the user who invited them

* Include `current_user` in new agent initialization parameters

* Add `shoulda-matchers` for testing associations

* Add Inviter information and associated account to welcome email

* Only show inviter info if applicable

* Update conversation spec for FFaker compatibility

spec/mailers/confirmation_instructions_spec.rb

@@ -0,0 +1,37 @@
+# frozen_string_literal: true
+
+require 'rails_helper' 
+
+RSpec.describe 'Confirmation Instructions', type: :mailer do
+  describe :notify do
+    let(:confirmable_user) { FactoryBot.build(:user, inviter: inviter_val) }
+    let(:inviter_val) { nil }
+    let(:mail) { confirmable_user.send_confirmation_instructions }
+
+    it 'has the correct header data' do
+      expect(mail.reply_to).to contain_exactly('accounts@chatwoot.com')
+      expect(mail.to).to contain_exactly(confirmable_user.email)
+      expect(mail.subject).to eq('Confirmation Instructions')
+    end
+
+    it 'uses the user\'s name' do
+      expect(mail.body).to match("Welcome, #{confirmable_user.name}!")
+    end
+
+    it 'does not refer to the inviter and their account' do
+      expect(mail.body).to_not match('has invited you to try out Chatwoot!')
+    end
+
+    context 'when there is an inviter' do
+      let(:inviter_val) do
+        FactoryBot.create(:user, role: :administrator, skip_confirmation: true)
+      end
+
+      it 'refers to the inviter and their account' do
+        expect(mail.body).to match(
+          "#{inviter_val.name}, with #{inviter_val.account.name}, has invited you to try out Chatwoot!"
+        )
+      end
+    end
+  end
+end