Add a test for the File.absolute_path method

mrbgems/mruby-io/test/file.rb

@@ -315,6 +315,11 @@ assert('File.expand_path (with getenv(3))') do
   assert_equal "#{MRubyIOTestUtil::ENV_HOME}/user", File.expand_path("user", MRubyIOTestUtil::ENV_HOME), "relative with base_dir"
 end
 
+assert('File.absolute_path') do
+  assert_equal File.expand_path("./~"), File.absolute_path("~")
+  assert_equal File.expand_path("./~user1"), File.absolute_path("~user1")
+end
+
 if MRubyIOTestUtil.win?
   assert('File.absolute_path? (for windows)') do
     assert_true File.absolute_path?("c:/")