Serde JSON nest digger

serde_json_dig.rs

use serde_json::Value;

#[derive(Debug)]
enum Shovel {
  Key(&'static str),
  Index(usize),
}

fn dig(val: Value, with: &[Shovel]) -> Option<Value> {
  if with.len() == 0 {
    return Some(val);
  }

  match with[0] {
    Shovel::Key(key) => {
      match val.as_object() {
        Some(dict) => {
          match dict.get(key) {
            Some(map_val) => dig(map_val.clone(), &with[1..with.len()]),
            None => None,
          }
        },
        None => None,
      }
    },
    Shovel::Index(i) => {
      match val.as_array() {
        Some(arr) => dig(arr[i].clone(), &with[1..with.len()]),
        None => None,
      }
    },
  }
}

#[test]
fn test_dig_object() {
  let data: Value = serde_json::from_str(r#"{"foo": "bar", "bar": [1, 2, 3]}"#).unwrap();
  let res = dig(data, &[Shovel::Key("foo")]);
  assert_eq!("bar", res.unwrap().as_str().unwrap());
}

#[test]
fn test_dig_array() {
  let data: Value = serde_json::from_str(r#"{"foo": "bar", "bar": [1, 2, 3]}"#).unwrap();
  let res = dig(data, &[Shovel::Key("bar"), Shovel::Index(2)]);
  assert_eq!(3, res.unwrap().as_i64().unwrap());
}

#[test]
fn test_dig_multiple_times() {
  let data: Value = serde_json::from_str(r#"{"foo": "bar", "bar": [1, 2, 3]}"#).unwrap();
  let res_data = dig(data.clone(), &[Shovel::Key("foo")]);
  let res_index = dig(data.clone(), &[Shovel::Key("bar"), Shovel::Index(2)]);
  assert_eq!("bar", res_data.unwrap().as_str().unwrap());
  assert_eq!(3, res_index.unwrap().as_i64().unwrap());
}

#[test]
fn dig_no_key() {
  let data: Value = serde_json::from_str(r#"{"foo": "bar", "bar": [1, 2, 3]}"#).unwrap();
  let res = dig(data, &[Shovel::Key("barbar")]);
  assert!(res.is_none());
}

#[test]
fn dig_wrong_type_not_object() {
  let data: Value = serde_json::from_str(r#"{"foo": "bar", "bar": [1, 2, 3]}"#).unwrap();
  let res = dig(data, &[Shovel::Key("bar"), Shovel::Key("foo")]);
  assert!(res.is_none());
}

#[test]
fn dig_wrong_type_not_array() {
  let data: Value = serde_json::from_str(r#"{"foo": "bar", "bar": [1, 2, 3]}"#).unwrap();
  let res = dig(data, &[Shovel::Index(2), Shovel::Index(1)]);
  assert!(res.is_none());
}