[Fix #757] Fix a false positive for Rails/ReflectionClassName

Fixes #757.

This PR fixes a false positive for `Rails/ReflectionClassName`
when using Ruby 3.1's hash shorthand syntax.

Author: koic

.rubocop_todo.yml

@@ -11,6 +11,7 @@ InternalAffairs/NodeDestructuring:
   Exclude:
     - 'lib/rubocop/cop/rails/environment_comparison.rb'
     - 'lib/rubocop/cop/rails/exit.rb'
+    - 'lib/rubocop/cop/rails/reflection_class_name.rb'
     - 'lib/rubocop/cop/rails/relative_date_constant.rb'
     - 'lib/rubocop/cop/rails/time_zone.rb'
 

changelog/fix_a_false_positive_for_rails_reflection_class_name.md

@@ -0,0 +1 @@
+* [#757](https://github.com/rubocop/rubocop-rails/issues/757): Fix a false positive for `Rails/ReflectionClassName` when using Ruby 3.1's hash shorthand syntax. ([@koic][])

lib/rubocop/cop/rails/reflection_class_name.rb

@@ -34,12 +34,29 @@ class ReflectionClassName < Base
 
         def on_send(node)
           association_with_reflection(node) do |reflection_class_name|
+            return if reflection_class_name.value.send_type? && reflection_class_name.value.receiver.nil?
+            return if reflection_class_name.value.lvar_type? && str_assigned?(reflection_class_name)
+
             add_offense(reflection_class_name.loc.expression)
           end
         end
 
         private
 
+        def str_assigned?(reflection_class_name)
+          lvar = reflection_class_name.value.source
+
+          reflection_class_name.ancestors.each do |nodes|
+            return true if nodes.each_child_node(:lvasgn).detect do |node|
+              lhs, rhs = *node
+
+              lhs.to_s == lvar && ALLOWED_REFLECTION_CLASS_TYPES.include?(rhs.type)
+            end
+          end
+
+          false
+        end
+
         def reflection_class_value?(class_value)
           if class_value.send_type?
             !class_value.method?(:to_s) || class_value.receiver&.const_type?

spec/rubocop/cop/rails/reflection_class_name_spec.rb

@@ -80,4 +80,52 @@
       belongs_to :account, class_name: :Account
     RUBY
   end
+
+  it 'registers an offense when parameter value is a local variable assigned a constant' do
+    expect_offense(<<~RUBY)
+      class_name = Account
+
+      has_many :accounts, class_name: class_name
+                          ^^^^^^^^^^^^^^^^^^^^^^ Use a string value for `class_name`.
+    RUBY
+  end
+
+  it 'does not register an offense when parameter value is a local variable assigned a string' do
+    expect_no_offenses(<<~RUBY)
+      class_name = 'Account'
+
+      has_many :accounts, class_name: class_name
+    RUBY
+  end
+
+  it 'does not register an offense when parameter value is a method call' do
+    expect_no_offenses(<<~RUBY)
+      has_many :accounts, class_name: class_name
+    RUBY
+  end
+
+  context 'Ruby >= 3.1', :ruby31 do
+    it 'registers an offense when shorthand syntax value is a local variable assigned a constant' do
+      expect_offense(<<~RUBY)
+        class_name = Account
+
+        has_many :accounts, class_name:
+                            ^^^^^^^^^^^ Use a string value for `class_name`.
+      RUBY
+    end
+
+    it 'does not register an offense when shorthand syntax value is a local variable assigned a string' do
+      expect_no_offenses(<<~RUBY)
+        class_name = 'Account'
+
+        has_many :accounts, class_name:
+      RUBY
+    end
+
+    it 'does not register an offense when shorthand syntax value is a local variable assigned a method call' do
+      expect_no_offenses(<<~RUBY)
+        has_many :accounts, class_name:
+      RUBY
+    end
+  end
 end