Squish username before validation (mastodon#10239)

* Squish username before validation (mastodon#10101)

Fix mastodon#10101

* Move before_validation hook to a private method

Also add Unicode wite-spaces to the spec to support the use of squish
over strip.

app/models/account.rb

@@ -473,6 +473,7 @@ def emojis
 
   before_create :generate_keys
   before_validation :prepare_contents, if: :local?
+  before_validation :prepare_username, on: :create
   before_destroy :clean_feed_manager
 
   private
@@ -482,6 +483,10 @@ def prepare_contents
     note&.strip!
   end
 
+  def prepare_username
+    username&.squish!
+  end
+
   def generate_keys
     return unless local? && !Rails.env.test?
 

spec/models/account_spec.rb

@@ -558,6 +558,11 @@
       expect(account).to model_have_error_on_field(:username)
     end
 
+    it 'squishes the username before validation' do
+      account = Fabricate(:account, domain: nil, username: " \u3000bob \t \u00a0 \n ")
+      expect(account.username).to eq 'bob'
+    end
+
     context 'when is local' do
       it 'is invalid if the username is not unique in case-insensitive comparison among local accounts' do
         account_1 = Fabricate(:account, username: 'the_doctor')