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.

spec/controllers/settings/profiles_controller_spec.rb

@@ -3,9 +3,11 @@ require 'rails_helper'
 RSpec.describe Settings::ProfilesController, type: :controller do
   render_views
 
+  let!(:user) { Fabricate(:user) }
+  let(:account) { user.account }
+
   before do
-    @user = Fabricate(:user)
-    sign_in @user, scope: :user
+    sign_in user, scope: :user
   end
 
   describe "GET #show" do
@@ -16,10 +18,12 @@ RSpec.describe Settings::ProfilesController, type: :controller do
   end
 
   describe 'PUT #update' do
+    before do
+      user.account.update(display_name: 'Old name')
+    end
+
     it 'updates the user profile' do
       allow(ActivityPub::UpdateDistributionWorker).to receive(:perform_async)
-      account = Fabricate(:account, user: @user, display_name: 'Old name')
-
       put :update, params: { account: { display_name: 'New name' } }
       expect(account.reload.display_name).to eq 'New name'
       expect(response).to redirect_to(settings_profile_path)
@@ -30,7 +34,6 @@ RSpec.describe Settings::ProfilesController, type: :controller do
   describe 'PUT #update with new profile image' do
     it 'updates profile image' do
       allow(ActivityPub::UpdateDistributionWorker).to receive(:perform_async)
-      account = Fabricate(:account, user: @user, display_name: 'AvatarTest')
       expect(account.avatar.instance.avatar_file_name).to be_nil
 
       put :update, params: { account: { avatar: fixture_file_upload('avatar.gif', 'image/gif') } }
@@ -43,7 +46,6 @@ RSpec.describe Settings::ProfilesController, type: :controller do
   describe 'PUT #update with oversized image' do
     it 'gives the user an error message' do
       allow(ActivityPub::UpdateDistributionWorker).to receive(:perform_async)
-      account = Fabricate(:account, user: @user, display_name: 'AvatarTest')
       put :update, params: { account: { avatar: fixture_file_upload('4096x4097.png', 'image/png') } }
       expect(response.body).to include('images are not supported')
     end