From 815d1198f96762082c23823bd9a74cac049f4a85 Mon Sep 17 00:00:00 2001
From: viralpraxis <iaroslav2k@gmail.com>
Date: Sat, 21 Dec 2024 16:06:42 +0300
Subject: [PATCH] Fix `Rails/FilePath` cop error on `join` method with implicit
 receiver

```console
echo 'join(Rails.root, path)' | rubocop --only Rails/FilePath  --stdin bug.rb -d

n error occurred while Rails/FilePath cop was inspecting bug.rb:1:0.
undefined method `each_node' for nil
lib/rubocop/cop/rails/file_path.rb:54:in `rails_root_nodes?'
lib/rubocop/cop/rails/file_path.rb:60:in `rails_root_join_nodes?'
lib/rubocop/cop/rails/file_path.rb:108:in `check_for_rails_root_join_with_string_arguments'
lib/rubocop/cop/rails/file_path.rb:70:in `on_send'
```
---
 changelog/fix_merge_pull_request_1392_from.md |  1 +
 lib/rubocop/cop/rails/file_path.rb            |  2 ++
 spec/rubocop/cop/rails/file_path_spec.rb      | 16 ++++++++++++++++
 3 files changed, 19 insertions(+)
 create mode 100644 changelog/fix_merge_pull_request_1392_from.md

diff --git a/changelog/fix_merge_pull_request_1392_from.md b/changelog/fix_merge_pull_request_1392_from.md
new file mode 100644
index 0000000000..887a3d16e5
--- /dev/null
+++ b/changelog/fix_merge_pull_request_1392_from.md
@@ -0,0 +1 @@
+* [#1397](https://github.com/rubocop/rubocop-rails/pull/1397): Fix `Rails/FilePath` cop error on `join` method with implicit receiver. ([@viralpraxis][])
diff --git a/lib/rubocop/cop/rails/file_path.rb b/lib/rubocop/cop/rails/file_path.rb
index 4bbbc92f6f..9c19c5e525 100644
--- a/lib/rubocop/cop/rails/file_path.rb
+++ b/lib/rubocop/cop/rails/file_path.rb
@@ -66,6 +66,8 @@ def on_dstr(node)
 
         def on_send(node)
           check_for_file_join_with_rails_root(node)
+          return unless node.receiver
+
           check_for_rails_root_join_with_slash_separated_path(node)
           check_for_rails_root_join_with_string_arguments(node)
         end
diff --git a/spec/rubocop/cop/rails/file_path_spec.rb b/spec/rubocop/cop/rails/file_path_spec.rb
index 27db8640c4..04d4cfd4e9 100644
--- a/spec/rubocop/cop/rails/file_path_spec.rb
+++ b/spec/rubocop/cop/rails/file_path_spec.rb
@@ -236,6 +236,14 @@
         RUBY
       end
     end
+
+    context 'with `join` method with implicit receiver' do
+      it 'does not register an offense' do
+        expect_no_offenses(<<~RUBY)
+          join(Rails.root, path)
+        RUBY
+      end
+    end
   end
 
   context 'when EnforcedStyle is `arguments`' do
@@ -420,5 +428,13 @@
         RUBY
       end
     end
+
+    context 'with `join` method with implicit receiver' do
+      it 'does not register an offense' do
+        expect_no_offenses(<<~RUBY)
+          join(Rails.root, path)
+        RUBY
+      end
+    end
   end
 end