Extend #ds_file? in Pathname

Library/Homebrew/extend/pathname.rb

@@ -457,6 +457,10 @@ class Pathname
     end
   end
 
+  def ds_store?
+    basename.to_s == ".DS_Store"
+  end
+
   # https://bugs.ruby-lang.org/issues/9915
   if RUBY_VERSION == "2.0.0"
     prepend Module.new {

Library/Homebrew/test/pathname_test.rb

@@ -166,6 +166,11 @@ class PathnameTests < Homebrew::TestCase
     @dir.cp_path_sub @src, @dst
     assert_predicate @dst/@dir.basename, :directory?
   end
+
+  def test_ds_store
+    refute_predicate @file, :ds_store?
+    assert_predicate @src/".DS_Store", :ds_store?
+  end
 end
 
 class PathnameInstallTests < Homebrew::TestCase