Refactor and improve tests (#17386)

* Change account and user fabricators to simplify and improve tests

- `Fabricate(:account)` implicitly fabricates an associated `user` if
  no `domain` attribute is given (an account with `domain: nil` is
  considered a local account, but no user record was created), unless
  `user: nil` is passed
- `Fabricate(:account, user: Fabricate(:user))` should still be possible
  but is discouraged.

* Fix and refactor tests

- avoid passing unneeded attributes to `Fabricate(:user)` or
  `Fabricate(:account)`
- avoid embedding `Fabricate(:user)` into a `Fabricate(:account)` or the other
  way around
- prefer `Fabricate(:user, account_attributes: …)` to
  `Fabricate(:user, account: Fabricate(:account, …)`
- also, some tests were using remote accounts with local user records, which is
  not representative of production code.

1 files changed, 1 insertions, 2 deletions

diff --git a/spec/controllers/settings/migrations_controller_spec.rb b/spec/controllers/settings/migrations_controller_spec.rb
index 048d9de8d..35c5747a0 100644
--- a/spec/controllers/settings/migrations_controller_spec.rb
+++ b/spec/controllers/settings/migrations_controller_spec.rb
@@ -19,8 +19,7 @@ describe Settings::MigrationsController do
     context 'when user is sign in' do
       subject { get :show }
 
-      let(:user) { Fabricate(:user, account: account) }
-      let(:account) { Fabricate(:account, moved_to_account: moved_to_account) }
+      let(:user) { Fabricate(:account, moved_to_account: moved_to_account).user }
 
       before { sign_in user, scope: :user }