`recognize` not consuming everything

[ThatOneShortGuy]

I figured a good way to get experience with nom is to write a JSON parser. Part of that is the number definition which forbids leading zeros (see json.org). I'm having trouble getting it to actually work. Everything else seems to be working but the whole numbers.

Minimal Example

#[test]
fn minimal_example() {
    let (un, val) = nom::combinator::recognize(nom::branch::alt((
        // exactly "0"
        nom::bytes::complete::tag::<_, _, nom::error::Error<&str>>("0"),
        // or <non-zero digit> then zero-or-more digits
        nom::combinator::recognize((
            nom::character::one_of("123456789"),
            nom::character::complete::digit0,
        )),
    )))
    .parse("123")
    .unwrap();

    assert_eq!(un, "");
    assert_eq!(val, "123");
}

Result

running 1 test
test tests::minimal_example ... FAILED

failures:

---- tests::minimal_example stdout ----

thread 'tests::minimal_example' panicked at src\main.rs:273:9:
assertion `left == right` failed
  left: "1"
 right: "123"
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace


failures:
    tests::minimal_example

test result: FAILED. 0 passed; 1 failed; 0 ignored; 0 measured; 9 filtered out; finished in 0.00s

I've spent a solid 4 hours on this now and have no clue what to do.