rubocop/no_fileutils_rmrf: Handle rmtree as an instance method

Library/Homebrew/rubocops/no_fileutils_rmrf.rb

@@ -4,7 +4,7 @@
 module RuboCop
   module Cop
     module Homebrew
-      # This cop checks for the use of `FileUtils.rm_f`, `FileUtils.rm_rf`, or `{FileUtils,Pathname}.rmtree`
+      # This cop checks for the use of `FileUtils.rm_f`, `FileUtils.rm_rf`, or `{FileUtils,instance}.rmtree`
       # and recommends the safer versions.
       class NoFileutilsRmrf < Base
         extend AutoCorrector
@@ -15,8 +15,8 @@ module RuboCop
           (send (const {nil? cbase} :FileUtils) {:rm_rf :rm_f :rmtree} ...)
         PATTERN
 
-        def_node_matcher :pathname_rm_r_f_tree?, <<~PATTERN
+        def_node_matcher :instance_rmtree?, <<~PATTERN
-          (send (const {nil? cbase} :Pathname) :rmtree ...)
+          (send (lvar ...) :rmtree ...)
         PATTERN
 
         def_node_matcher :self_rm_r_f_tree?, <<~PATTERN
@@ -31,20 +31,26 @@ module RuboCop
           return if neither_rm_rf_nor_rmtree?(node)
 
           add_offense(node) do |corrector|
-            class_name = "FileUtils." if fileutils_rm_r_f_tree?(node) || pathname_rm_r_f_tree?(node)
+            class_name = "FileUtils." if fileutils_rm_r_f_tree?(node) || instance_rmtree?(node)
             new_method = if node.method?(:rm_rf) || node.method?(:rmtree)
               "rm_r"
             else
               "rm"
             end
 
-            corrector.replace(node.loc.expression, "#{class_name}#{new_method}(#{node.arguments.first.source})")
+            args = if instance_rmtree?(node)
+              node.receiver.source
+            else
+              node.arguments.first.source
+            end
+
+            corrector.replace(node.loc.expression, "#{class_name}#{new_method}(#{args})")
           end
         end
 
         def neither_rm_rf_nor_rmtree?(node)
           !self_rm_r_f_tree?(node) && !plain_rm_r_f_tree?(node) &&
-            !fileutils_rm_r_f_tree?(node) && !pathname_rm_r_f_tree?(node)
+            !fileutils_rm_r_f_tree?(node) && !instance_rmtree?(node)
         end
       end
     end

Library/Homebrew/sorbet/rbi/dsl/rubo_cop/cop/homebrew/no_fileutils_rmrf.rbi

@@ -10,7 +10,7 @@ class RuboCop::Cop::Homebrew::NoFileutilsRmrf
   def fileutils_rm_r_f_tree?(node, **kwargs, &block); end
 
   sig { params(node: RuboCop::AST::Node, kwargs: T.untyped, block: T.untyped).returns(T.untyped) }
-  def pathname_rm_r_f_tree?(node, **kwargs, &block); end
+  def instance_rmtree?(node, **kwargs, &block); end
 
   sig { params(node: RuboCop::AST::Node, kwargs: T.untyped, block: T.untyped).returns(T.untyped) }
   def plain_rm_r_f_tree?(node, **kwargs, &block); end

Library/Homebrew/test/rubocops/no_fileutils_rmrf_spec.rb

@@ -56,20 +56,23 @@ RSpec.describe RuboCop::Cop::Homebrew::NoFileutilsRmrf do
       expect_offense(<<~RUBY)
         rmtree("path/to/directory")
         ^^^^^^^^^^^^^^^^^^^^^^^^^^^ Homebrew/NoFileutilsRmrf: #{RuboCop::Cop::Homebrew::NoFileutilsRmrf::MSG}
-        Pathname.rmtree("path/to/other/directory")
+        other_dir = Pathname("path/to/other/directory")
-        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Homebrew/NoFileutilsRmrf: #{RuboCop::Cop::Homebrew::NoFileutilsRmrf::MSG}
+        other_dir.rmtree
+        ^^^^^^^^^^^^^^^^ Homebrew/NoFileutilsRmrf: #{RuboCop::Cop::Homebrew::NoFileutilsRmrf::MSG}
       RUBY
     end
 
     it "autocorrects" do
       corrected = autocorrect_source(<<~RUBY)
         rmtree("path/to/directory")
-        Pathname.rmtree("path/to/other/directory")
+        other_dir = Pathname("path/to/other/directory")
+        other_dir.rmtree
       RUBY
 
       expect(corrected).to eq(<<~RUBY)
         rm_r("path/to/directory")
-        FileUtils.rm_r("path/to/other/directory")
+        other_dir = Pathname("path/to/other/directory")
+        FileUtils.rm_r(other_dir)
       RUBY
     end
   end