Tests with mismatched types

[mlevkov]

Hello,

I've discovered your library. Thank you for putting it together.
While looking through test cases, I've noticed that assert_eq! has mismatched types.
For example

assert_eq!(root.find_child(|t| t.name == "child"), Some(&child));

comparing to "child" assuming that it is String whereas t.name is a String, but "child" is of &str type.
May I suggest altering assert_eq! to the following

assert_eq!(root.find_child(|t| t.name == "child".to_owned()), Some(&child));

Assuming that if that it is your intention to compare t.name to "child" as String type.