Return value from transaction yield to caller instead of internal state (mongodb#6005)

Co-authored-by: Dmitry Rybakov <[email protected]>

Author: drcapulet

lib/mongoid/clients/sessions.rb

@@ -92,8 +92,7 @@ def transaction(options = {}, session_options: {})
             begin
               session.with_transaction(options) do
                 yield
-              end
-              run_commit_callbacks(session)
+              end.tap { run_commit_callbacks(session) }
             rescue *transactions_not_supported_exceptions
               raise Mongoid::Errors::TransactionsNotSupported
             rescue Mongoid::Errors::Rollback

spec/mongoid/clients/transactions_spec.rb

@@ -716,7 +716,7 @@ def capture_exception
       require_transaction_support
 
       context 'when no error raised' do
-        before do
+        let!(:person) do
           Mongoid.transaction do
             Person.create!
           end
@@ -727,6 +727,10 @@ def capture_exception
           expect(other_events.count { |e| e.command_name == 'commitTransaction'}).to be(1)
         end
 
+        it 'returns the value from the block' do
+          expect(person).to be_a(Person)
+        end
+
         it 'executes the commands inside the transaction' do
           expect(Person.count).to be(1)
         end