Rename ActiveStorage::Filename#extname to extension_with_delimiter

activestorage/app/models/active_storage/filename.rb

@@ -9,21 +9,23 @@ class ActiveStorage::Filename
     @filename = filename
   end
 
-  # Filename.new("racecar.jpg").extname # => ".jpg"
-  def extname
-    File.extname(@filename)
-  end
-
-  # Filename.new("racecar.jpg").extension # => "jpg"
-  def extension
-    extname.from(1)
-  end
-
   # Filename.new("racecar.jpg").base # => "racecar"
   def base
-    File.basename(@filename, extname)
+    File.basename @filename, extension_with_delimiter
   end
 
+  # Filename.new("racecar.jpg").extension_with_delimiter # => ".jpg"
+  def extension_with_delimiter
+    File.extname @filename
+  end
+
+  # Filename.new("racecar.jpg").extension_without_delimiter # => "jpg"
+  def extension_without_delimiter
+    extension_with_delimiter.from(1).to_s
+  end
+
+  alias_method :extension, :extension_without_delimiter
+
   # Filename.new("foo:bar.jpg").sanitized # => "foo-bar.jpg"
   # Filename.new("foo/bar.jpg").sanitized # => "foo-bar.jpg"
   #

activestorage/test/models/filename_test.rb

@@ -3,6 +3,24 @@
 require "test_helper"
 
 class ActiveStorage::FilenameTest < ActiveSupport::TestCase
+  test "base" do
+    assert_equal "racecar", ActiveStorage::Filename.new("racecar.jpg").base
+    assert_equal "race.car", ActiveStorage::Filename.new("race.car.jpg").base
+    assert_equal "racecar", ActiveStorage::Filename.new("racecar").base
+  end
+
+  test "extension with delimiter" do
+    assert_equal ".jpg", ActiveStorage::Filename.new("racecar.jpg").extension_with_delimiter
+    assert_equal ".jpg", ActiveStorage::Filename.new("race.car.jpg").extension_with_delimiter
+    assert_equal "", ActiveStorage::Filename.new("racecar").extension_with_delimiter
+  end
+
+  test "extension without delimiter" do
+    assert_equal "jpg", ActiveStorage::Filename.new("racecar.jpg").extension_without_delimiter
+    assert_equal "jpg", ActiveStorage::Filename.new("race.car.jpg").extension_without_delimiter
+    assert_equal "", ActiveStorage::Filename.new("racecar").extension_without_delimiter
+  end
+
   test "sanitize" do
     "%$|:;/\t\r\n\\".each_char do |character|
       filename = ActiveStorage::Filename.new("foo#{character}bar.pdf")