test for the Jekyll's issue #1519: Liquid doesn't render my partial

I have written three tests to determine Jekyll's issue #1519, [Liquid doesn't render my partial](https://github.com/mojombo/jekyll/issues/1519), is caused by Liquid or not. Finally, I have got the fact that Liquid isn't wrong.

If these tests are useless for you, just ignore it.

Thanks,
Hideto