actix-web + serde_urlencoded

Result1.txt

---- deserialize_option stdout ----
thread 'deserialize_option' panicked at 'assertion failed: `(left == right)`
  left: `Ok([("last", Some(42))])`,
 right: `Ok([("first", None), ("last", Some(42))])`', tests/test_deserialize.rs:59:5
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace.

Result2.txt

thread 'deserialize_option' panicked at 'assertion failed: `(left == right)`
  left: `Err(Error { err: "cannot parse integer from empty string" })`,
 right: `Ok([("first", None), ("last", Some(42))])`', tests/test_deserialize.rs:59:5
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace.

Test1.rs

#[test]
fn deserialize_option() {
    // Original
    let result = vec![
        ("first".to_owned(), Some(23)),
        ("last".to_owned(), Some(42)),
    ];
    assert_eq!(serde_urlencoded::from_str("first=23&last=42"), Ok(result));

    // Added by me
    let result =
        vec![("first".to_owned(), None), ("last".to_owned(), Some(42))];
    assert_eq!(serde_urlencoded::from_str("last=42"), Ok(result));
}

Test2.rs

#[test]
fn deserialize_option() {
    // Original
    let result = vec![
        ("first".to_owned(), Some(23)),
        ("last".to_owned(), Some(42)),
    ];
    assert_eq!(serde_urlencoded::from_str("first=23&last=42"), Ok(result));

    // Added by me
    let result =
        vec![("first".to_owned(), None), ("last".to_owned(), Some(42))];
    assert_eq!(serde_urlencoded::from_str("first=&last=42"), Ok(result));
}