serde_test  

This crate provides a convenient concise way to write unit tests for implementations of Serialize and Deserialize.

The Serialize impl for a value can be characterized by the sequence of Serializer calls that are made in the course of serializing the value, so serde_test provides a [Token] abstraction which corresponds roughly to Serializer method calls. There is an [assert_ser_tokens] function to test that a value serializes to a particular sequence of method calls, an [assert_de_tokens] function to test that a value can be deserialized from a particular sequence of method calls, and an [assert_tokens] function to test both directions. There are also functions to test expected failure conditions.

Here is an example from the linked-hash-map crate.

use linked_hash_map::LinkedHashMap;
use serde_test::{assert_tokens, Token};

#[test]
fn test_ser_de_empty() {
    let map = LinkedHashMap::<char, u32>::new();

    assert_tokens(
        &map,
        &[
            Token::Map { len: Some(0) },
            Token::MapEnd,
        ],
    );
}

#[test]
fn test_ser_de() {
    let mut map = LinkedHashMap::new();
    map.insert('b', 20);
    map.insert('a', 10);
    map.insert('c', 30);

    assert_tokens(
        &map,
        &[
            Token::Map { len: Some(3) },
            Token::Char('b'),
            Token::I32(20),
            Token::Char('a'),
            Token::I32(10),
            Token::Char('c'),
            Token::I32(30),
            Token::MapEnd,
        ],
    );
}

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