spec/models/user_spec.rb

@@ -16,6 +16,10 @@ RSpec.describe User, type: :model do
     let(:user) { build :user, cn: "jimmy", ou: "kosmos.org" }
 
     context "Mastodon service not configured" do
+      before do
+        Setting.mastodon_enabled = false
+      end
+
       it "returns nil" do
         expect(user.mastodon_address).to be_nil
       end