Add specs for BlackListedEmailValidator (#9651)

* Add specs for BlackListedEmailValidator

* Use instance variable

spec/validators/blacklisted_email_validator_spec.rb

@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+
+require 'rails_helper'
+
+RSpec.describe BlacklistedEmailValidator, type: :validator do
+  describe '#validate' do
+    let(:user)   { double(email: 'info@mail.com', errors: errors) }
+    let(:errors) { double(add: nil) }
+
+    before do
+      allow_any_instance_of(described_class).to receive(:blocked_email?) { blocked_email }
+      described_class.new.validate(user)
+    end
+
+    context 'blocked_email?' do
+      let(:blocked_email) { true }
+
+      it 'calls errors.add' do
+        expect(errors).to have_received(:add).with(:email, I18n.t('users.invalid_email'))
+      end
+    end
+
+    context '!blocked_email?' do
+      let(:blocked_email) { false }
+
+      it 'not calls errors.add' do
+        expect(errors).not_to have_received(:add).with(:email, I18n.t('users.invalid_email'))
+      end
+    end
+  end
+end