added nested transaction rollback handling and updated specs

Author: klobuczek

lib/active_graph/transaction.rb

@@ -1,7 +1,11 @@
 module ActiveGraph
   module Transaction
     def rollback
-      fail ActiveGraph::Rollback
+      @rolled_back = true
+    end
+
+    def check_rollback
+      fail ActiveGraph::Rollback if @rolled_back
     end
 
     def after_commit(&block)

lib/active_graph/transactions.rb

@@ -42,24 +42,27 @@ def send_transaction(method, **config, &block)
         end
       end
 
-      def run_transaction_work(session, method, **config, &block)
-        implicit = config.delete(:implicit)
+      def run_transaction_work(session, method, implicit: false, **config, &block)
+        result = nil
         session.send(method, **config) do |tx|
           self.tx = tx
-          block.call(tx).tap do |result|
-            if implicit &&
-              [Core::Result, ActiveGraph::Node::Query::QueryProxy, ActiveGraph::Core::Query]
-                .any?(&result.method(:is_a?))
-              result.store
-            end
+          (result = block.call(tx)).tap do
+            store(it) if implicit
+            tx.check_rollback
           end
         end.tap { tx.apply_callbacks }
       rescue ActiveGraph::Rollback
         # rollbacks are silently swallowed
-        false # to satisfy save and update conventions
+        result
       ensure
         self.tx = nil
       end
+
+      def store(result)
+        if [Core::Result, ActiveGraph::Node::Query::QueryProxy, ActiveGraph::Core::Query].any?(&result.method(:is_a?))
+          result.store
+        end
+      end
     end
   end
 end

spec/active_graph/transactions_spec.rb

@@ -122,4 +122,33 @@
       end
     end
   end
+
+  describe 'rollback in nested transaction' do
+    it 'returns the result from the inner transaction when rollback is called' do
+      inner_result = nil
+      ActiveGraph::Base.transaction do
+        inner_result = ActiveGraph::Base.transaction do |tx|
+          tx.rollback
+          'inner result'
+        end
+      end
+      expect(inner_result).to eq 'inner result'
+    end
+
+    it 'allows reading model errors after failed update inside an outer transaction' do
+      stub_node_class('ValidatedStudent') do
+        property :name
+        validates :name, presence: true
+      end
+
+      student = ValidatedStudent.create!(name: 'Alice')
+
+      errors = ActiveGraph::Base.transaction do
+        student.update(name: nil)
+        student.errors.full_messages
+      end
+
+      expect(errors).to include("Name can't be blank")
+    end
+  end
 end