Add missing tests for sessions controller (#7744)

spec/controllers/settings/sessions_controller_spec.rb

+require 'rails_helper'
+
+describe Settings::SessionsController do
+  render_views
+
+  let(:user) { Fabricate(:user) }
+  let(:session_activation) { Fabricate(:session_activation, user: user) }
+  before { sign_in user, scope: :user }
+
+  describe 'DELETE #destroy' do
+    subject { delete :destroy, params: { id: id } }
+
+    context 'when session activation exists' do
+      let(:id) { session_activation.id }
+
+      it 'destroys session activation' do
+        is_expected.to redirect_to edit_user_registration_path
+        expect(SessionActivation.find_by(id: id)).to be_nil
+      end
+    end
+
+    context 'when session activation does not exist' do
+      let(:id) { session_activation.id + 1000 }
+
+      it 'destroys session activation' do
+        is_expected.to have_http_status :not_found
+      end
+    end
+  end
+end