Merge pull request #1421 from ydakuka/fix/enhance-rails-save-bang-to-properly-handle-instance-variables

[Fix #1228] Enhance `Rails/SaveBang` to properly handle instance variables

Author: koic

changelog/fix_rails_save_bang_to_handle_instance_variables.md

@@ -0,0 +1 @@
+* [#1228](https://github.com/rubocop/rubocop-rails/issues/1228): Enhance `Rails/SaveBang` to properly handle instance variables. ([@ydakuka][])

lib/rubocop/cop/rails/save_bang.rb

@@ -328,8 +328,9 @@ def explicit_return?(node)
         end
 
         def return_value_assigned?(node)
-          assignment = assignable_node(node).parent
-          assignment&.lvasgn_type?
+          return false unless (assignment = assignable_node(node).parent)
+
+          assignment.assignment?
         end
 
         def persist_method?(node, methods = RESTRICT_ON_SEND)

spec/rubocop/cop/rails/save_bang_spec.rb

@@ -668,6 +668,56 @@ def whatever
       RUBY
     end
 
+    it "does not register an offense when using persisted? after #{method} to a local variable" do
+      expect_no_offenses(<<~RUBY)
+        user = User.#{method}
+
+        if user.persisted?
+          foo
+        end
+      RUBY
+    end
+
+    it "does not register an offense when using persisted? after #{method} to an instance variable" do
+      expect_no_offenses(<<~RUBY)
+        @user = User.#{method}
+
+        if @user.persisted?
+          foo
+        end
+      RUBY
+    end
+
+    it "does not register an offense when using persisted? after #{method} to a global variable" do
+      expect_no_offenses(<<~RUBY)
+        $user = User.#{method}
+
+        if $user.persisted?
+          foo
+        end
+      RUBY
+    end
+
+    it "does not register an offense when using persisted? after #{method} for multiple assignments" do
+      expect_no_offenses(<<~RUBY)
+        a, b = User.#{method}, User.new
+
+        if a.persisted?
+          foo
+        end
+      RUBY
+    end
+
+    it "does not register an offense when using persisted? after #{method} for conditional assignments" do
+      expect_no_offenses(<<~RUBY)
+        user ||= User.#{method}
+
+        if user.persisted?
+          foo
+        end
+      RUBY
+    end
+
     it "when using #{method} with `||`" do
       expect_no_offenses(<<~RUBY)
         def find_or_create(**opts)