assert_tokens reports failure to deserialize but actual deserialization works

[mkpankov]

I have the following test code:

#[macro_use]
extern crate serde_derive;
extern crate serde;
extern crate serde_json;
extern crate serde_test;

use serde_test::{assert_tokens, Token};

#[derive(Serialize, Deserialize, Debug, PartialEq, Eq)]
pub struct VecWrapper(pub Vec<u8>);

#[derive(Serialize, Deserialize, Debug, PartialEq)]
#[serde(untagged)]
pub enum Enum {
    Str(String),
    Vector(VecWrapper),
    Number(f64),
    Boolean(bool),
    Nil,
    Other,
}

fn main() {
    let v = Enum::Vector(VecWrapper(vec![b'a', b'b', b'c']));
    let s = serde_json::to_string(&v).unwrap();
    println!("{:?}", s);
    let v_: Enum = serde_json::from_str(&*s).unwrap();
    assert_eq!(v, v_);

    assert_tokens(
        &v,
        &[
            Token::NewtypeStruct { name: "VecWrapper" },
            Token::Seq { len: Some(3) },
            Token::U8(97),
            Token::U8(98),
            Token::U8(99),
            Token::SeqEnd,
        ],
    );
}

With this, I get following output:

"[97,98,99]"
thread 'main' panicked at 'tokens failed to deserialize: data did not match any variant of untagged enum Enum', /home/mkpankov/.cargo/registry/src/github.com-1ecc6299db9ec823/serde_test-1.0.42/src/assert.rs:192:19

I don't get why assert_tokens fails while serde_json::from_str succeeds. At the data model level everything should be the same?

Full project source.

[dtolnay]

Thanks! This was a bug. I published 1.0.43 with a fix and your test should work as written.