Hack in registration prevention (#37)

Reviewed-on: #37

test/test_helper.rb

@@ -14,4 +14,15 @@ class ActiveSupport::TestCase
     post sessions_url, params: { session: { email: email, password: password } }
     assert session[:current_user_id].present?
   end
+
+  def stub_environment(env)
+    old_env = ENV.to_hash
+    ENV.update(env.stringify_keys)
+
+    begin
+      yield
+    ensure
+      ENV.replace(old_env)
+    end
+  end
 end