DEV: Allow DB.after_commit to be used outside of a transaction

In this case, it will execute the given block immediately

lib/mini_sql_multisite_connection.rb

@@ -43,8 +43,16 @@ class MiniSqlMultisiteConnection < MiniSql::Postgres::Connection
   end
 
   # Allows running arbitrary code after the current transaction has been committed.
-  # Works even with nested transactions. Useful for scheduling sidekiq jobs.
+  # Works with nested ActiveRecord transaction blocks. Useful for scheduling sidekiq jobs.
+  # If not currently in a transaction, will execute immediately
   def after_commit(&blk)
+    return blk.call if !ActiveRecord::Base.connection.transaction_open?
+
+    # In tests, everything is run inside a transaction.
+    # To run immediately, check for joinable? transaction
+    # This mimics core rails behavior: https://github.com/rails/rails/blob/348e142b/activerecord/lib/active_record/connection_adapters/abstract/transaction.rb#L211
+    return blk.call if Rails.env.test? && !ActiveRecord::Base.connection.current_transaction.joinable?
+
     ActiveRecord::Base.connection.add_transaction_record(
       AfterCommitWrapper.new(&blk)
     )

spec/lib/mini_sql_multisite_connection_spec.rb

@@ -49,6 +49,19 @@ describe MiniSqlMultisiteConnection do
 
       expect(outputString).to eq("123")
     end
+
+    it "runs immediately if there is no transaction" do
+      outputString = "1"
+
+      DB.after_commit do
+        outputString += "2"
+      end
+
+      outputString += "3"
+
+      expect(outputString).to eq("123")
+    end
+
   end
 
 end