From 334e5cc394afdac3bc36ad24ceac577fbbe557c2 Mon Sep 17 00:00:00 2001
From: Yauheni Dakuka <yauheni.dakuka@gmail.com>
Date: Sat, 18 Jan 2025 17:04:16 +0400
Subject: [PATCH] [Fix rubocop#1389] Handle TypeError caused by an array in
 Rails/RootPathname cop

---
 ...to_handle_type_error_caused_by_an_array.md |  1 +
 .../cop/rails/root_pathname_methods.rb        |  7 +-
 .../cop/rails/root_pathname_methods_spec.rb   | 66 +++++++++++++++++++
 3 files changed, 73 insertions(+), 1 deletion(-)
 create mode 100644 changelog/fix_rails_root_pathname_to_handle_type_error_caused_by_an_array.md

diff --git a/changelog/fix_rails_root_pathname_to_handle_type_error_caused_by_an_array.md b/changelog/fix_rails_root_pathname_to_handle_type_error_caused_by_an_array.md
new file mode 100644
index 0000000000..8c77d4b0b3
--- /dev/null
+++ b/changelog/fix_rails_root_pathname_to_handle_type_error_caused_by_an_array.md
@@ -0,0 +1 @@
+* [#1389](https://github.com/rubocop/rubocop-rails/issues/1389): Handle `TypeError` caused by passing array literals as arguments to `File` methods in `Rails/RootPathnameMethods` cop. ([@ydakuka][])
diff --git a/lib/rubocop/cop/rails/root_pathname_methods.rb b/lib/rubocop/cop/rails/root_pathname_methods.rb
index 5898d0b421..1678d51c47 100644
--- a/lib/rubocop/cop/rails/root_pathname_methods.rb
+++ b/lib/rubocop/cop/rails/root_pathname_methods.rb
@@ -237,7 +237,12 @@ def build_path_replacement(path, method, args)
           end
 
           replacement = "#{path_replacement}.#{method}"
-          replacement += "(#{args.map(&:source).join(', ')})" unless args.empty?
+
+          if args.any?
+            formatted_args = args.map { |arg| arg.array_type? ? "*#{arg.source}" : arg.source }
+            replacement += "(#{formatted_args.join(', ')})"
+          end
+
           replacement
         end
 
diff --git a/spec/rubocop/cop/rails/root_pathname_methods_spec.rb b/spec/rubocop/cop/rails/root_pathname_methods_spec.rb
index 82f00ea5da..77cb1b1218 100644
--- a/spec/rubocop/cop/rails/root_pathname_methods_spec.rb
+++ b/spec/rubocop/cop/rails/root_pathname_methods_spec.rb
@@ -210,4 +210,70 @@
       file = Rails.root.join('docs', 'invoice.pdf').open
     RUBY
   end
+
+  it 'registers an offense when using only [] syntax' do
+    expect_offense(<<~RUBY)
+      File.join(Rails.root, ['app', 'models'])
+      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `Rails.root` is a `Pathname`, so you can use `Rails.root.join(*['app', 'models'])`.
+    RUBY
+
+    expect_correction(<<~RUBY)
+      Rails.root.join(*['app', 'models'])
+    RUBY
+  end
+
+  it 'registers an offense when using a leading string and an array using [] syntax' do
+    expect_offense(<<~RUBY)
+      File.join(Rails.root, "app", ["models", "goober"])
+      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `Rails.root` is a `Pathname`, so you can use `Rails.root.join("app", *["models", "goober"])`.
+    RUBY
+
+    expect_correction(<<~RUBY)
+      Rails.root.join("app", *["models", "goober"])
+    RUBY
+  end
+
+  it 'registers an offense when using an array using [] syntax and a trailing string' do
+    expect_offense(<<~RUBY)
+      File.join(Rails.root, ["app", "models"], "goober")
+      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `Rails.root` is a `Pathname`, so you can use `Rails.root.join(*["app", "models"], "goober")`.
+    RUBY
+
+    expect_correction(<<~RUBY)
+      Rails.root.join(*["app", "models"], "goober")
+    RUBY
+  end
+
+  it 'registers an offense when using only %w[] syntax' do
+    expect_offense(<<~RUBY)
+      File.join(Rails.root, %w[app models])
+      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `Rails.root` is a `Pathname`, so you can use `Rails.root.join(*%w[app models])`.
+    RUBY
+
+    expect_correction(<<~RUBY)
+      Rails.root.join(*%w[app models])
+    RUBY
+  end
+
+  it 'registers an offense when using a leading string and an array using %w[] syntax' do
+    expect_offense(<<~RUBY)
+      File.join(Rails.root, "app", %w[models goober])
+      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `Rails.root` is a `Pathname`, so you can use `Rails.root.join("app", *%w[models goober])`.
+    RUBY
+
+    expect_correction(<<~RUBY)
+      Rails.root.join("app", *%w[models goober])
+    RUBY
+  end
+
+  it 'registers an offense when using an array using %w[] syntax and a trailing string' do
+    expect_offense(<<~RUBY)
+      File.join(Rails.root, %w[app models], "goober")
+      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `Rails.root` is a `Pathname`, so you can use `Rails.root.join(*%w[app models], "goober")`.
+    RUBY
+
+    expect_correction(<<~RUBY)
+      Rails.root.join(*%w[app models], "goober")
+    RUBY
+  end
 end