Use the actual search and author base

The `author` and `search` bases can be changed. Might as well support this in the default tests.

To change your author or search base to test:

```php
add_action( 'init', function() {
    global $wp_rewrite;
    $wp_rewrite->author_base = 'publisher';
    $wp_rewrite->search_base = 'find';
} );
```