From 5e2237a83ecd3b0277ec9e1ef96ee257af6681d5 Mon Sep 17 00:00:00 2001
From: Earlopain <14981592+Earlopain@users.noreply.github.com>
Date: Thu, 22 Aug 2024 16:55:52 +0200
Subject: [PATCH] Fix an error for `Rails/Validation` when passing no arguments

---
 changelog/fix_error_rails_validation.md   | 1 +
 lib/rubocop/cop/rails/validation.rb       | 2 +-
 spec/rubocop/cop/rails/validation_spec.rb | 6 ++++++
 3 files changed, 8 insertions(+), 1 deletion(-)
 create mode 100644 changelog/fix_error_rails_validation.md

diff --git a/changelog/fix_error_rails_validation.md b/changelog/fix_error_rails_validation.md
new file mode 100644
index 0000000000..024d4bf8b9
--- /dev/null
+++ b/changelog/fix_error_rails_validation.md
@@ -0,0 +1 @@
+* [#1337](https://github.com/rubocop/rubocop-rails/pull/1337): Fix an error for `Rails/Validation` when passing no arguments. ([@earlopain][])
diff --git a/lib/rubocop/cop/rails/validation.rb b/lib/rubocop/cop/rails/validation.rb
index beaa8f2b6e..bc78b01625 100644
--- a/lib/rubocop/cop/rails/validation.rb
+++ b/lib/rubocop/cop/rails/validation.rb
@@ -59,11 +59,11 @@ class Validation < Base
 
         def on_send(node)
           return if node.receiver
+          return unless (last_argument = node.last_argument)
 
           range = node.loc.selector
 
           add_offense(range, message: message(node)) do |corrector|
-            last_argument = node.last_argument
             return if !last_argument.literal? && !last_argument.splat_type? && !frozen_array_argument?(last_argument)
 
             corrector.replace(range, 'validates')
diff --git a/spec/rubocop/cop/rails/validation_spec.rb b/spec/rubocop/cop/rails/validation_spec.rb
index 3aa2b891f9..c178b371d3 100644
--- a/spec/rubocop/cop/rails/validation_spec.rb
+++ b/spec/rubocop/cop/rails/validation_spec.rb
@@ -171,4 +171,10 @@
       validates_numericality_of :a, b
     RUBY
   end
+
+  it 'registers no offense when no arguments are passed' do
+    expect_no_offenses(<<~RUBY)
+      validates_numericality_of
+    RUBY
+  end
 end