1 files changed, 11 insertions, 0 deletions
diff --git a/test/rdoc/test_rdoc_options.rb b/test/rdoc/test_rdoc_options.rb
index d53acf2a6c..5d7135c795 100644
--- a/test/rdoc/test_rdoc_options.rb
+++ b/test/rdoc/test_rdoc_options.rb
@@ -549,6 +549,17 @@ rdoc_include:
     FileUtils.rm_rf tmpdir
   end
 
+  def test_parse_extension_alias
+    out, err = capture_io do
+      @options.parse %w[--extension foobar=rdoc]
+    end
+
+    assert_includes RDoc::Parser.parsers, [/\.foobar$/, RDoc::Parser::Simple]
+
+    assert_empty out
+    assert_empty err
+  end
+
   def test_setup_generator
     test_generator = Class.new do
       def self.setup_options op