bump coverage by testing more edge cases

mime type detector using file, no idnx

standalone_tests/no_punycode_test.rb

@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+$LOAD_PATH.delete_if { |path| path.include?("/idnx") }
+
+require "test_helper"
+require "support/http_helpers"
+require "support/minitest_extensions"
+
+class NoPunycodeTest < Minitest::Test
+  include HTTPHelpers
+
+  def test_do_not_punycode
+    assert_raises(URI::InvalidComponentError) do
+      HTTPX.get("http://bücher.ch")
+    end
+  end
+end