convert_front_ok

#[test]
    fn convert_front_ok() {
        let res = JkDocument::convert_front(Some(CORRECT_JK_FRONT.to_owned()));
        match res {
            Err(e) => println!("error convert: {:#?}", e),
            Ok(mut converted) => {
                // need to remove the custom part, the fields order is not stable
                let custom_offset = converted.find("custom").unwrap_or(converted.len());
                let all_but_custom: String = converted.drain(..custom_offset).collect();
                assert_eq!(all_but_custom, CORRECT_CB_FRONT);
                let customs_builder: FrontmatterBuilder = serde_yaml::from_str(&converted).unwrap();
                let customs: frontmatter::Frontmatter = customs_builder.build().ok().unwrap();

                let expected: HashMap<String, liquid::Value> =
                    [("guid", liquid::Value::str("\"http://url.com/?p=33\"")),
                     ("id", liquid::Value::Num(33.0f32)),
                     ("author", liquid::Value::str("TheAuthor")),
                     ("tags",
                      liquid::Value::Array(vec![liquid::Value::str("tag1"),
                                                liquid::Value::str("tag2")]))]
                            .iter()
                            .cloned()
                            .collect();
                assert_eq!(expected, customs.custom);
            }
        }
    }