Fix bug caused when factory block is empty

Author: r7kamura

lib/rubocop/cop/rspec/factory_bot/association_style.rb

@@ -141,6 +141,7 @@ def children_of_factory_block(node)
             block = node.parent
             return [] unless block
             return [] unless block.block_type?
+            return [] unless block.body
 
             if block.body.begin_type?
               block.body.children

spec/rubocop/cop/rspec/factory_bot/association_style_spec.rb

@@ -12,6 +12,23 @@ def inspected_source_filename
   context 'when EnforcedStyle is :implicit' do
     let(:enforced_style) { :implicit }
 
+    context 'when factory block is empty' do
+      it 'does not register an offense' do
+        expect_no_offenses(<<~RUBY)
+          factory :user do
+          end
+        RUBY
+      end
+    end
+
+    context 'with when factory has no block' do
+      it 'does not register an offense' do
+        expect_no_offenses(<<~RUBY)
+          factory :user
+        RUBY
+      end
+    end
+
     context 'when implicit style is used' do
       it 'does not register an offense' do
         expect_no_offenses(<<~RUBY)