Crate serde_assert

Testing library for serde Serialize and Deserialize implementations.

This library provides a Serializer and Deserializer to be used in writing unit tests to assert the behavior of manual Serialize and Deserialize implementations, respectively. The implementation behavior can be verified by using a sequence of Tokens representing an arbitrary serialized state.

Testing Serialization

The Serializer returns a sequence of Tokens representing the serialization of a value. The returned Tokens can be checked to be equal to an expected value. Since Serialize::serialize() returns a Result<Tokens, Error>, it is recommended to use the claims crate to check that the returned value is both Ok and equal to the expected sequence of Tokens.

use claims::assert_ok_eq;
use serde::Serialize;
use serde_assert::{
    Serializer,
    Token,
};

let serializer = Serializer::builder().build();

assert_ok_eq!(true.serialize(&serializer), [Token::Bool(true)]);

Arbitrary Ordering

In cases where the ordering of Tokens does not matter, such as when serializing a HashSet, Token::Unordered can be used to specify that tokens can be in an arbitrary order.

use claims::assert_ok_eq;
use serde::Serialize;
use serde_assert::{
    Serializer,
    Token,
};
use std::collections::HashSet;

let serializer = Serializer::builder().build();

let mut set = HashSet::<u32>::new();
set.insert(1);
set.insert(2);
set.insert(3);

assert_ok_eq!(
    set.serialize(&serializer),
    [
        Token::Seq { len: Some(3) },
        Token::Unordered(&[&[Token::U32(1)], &[Token::U32(2)], &[Token::U32(3)],]),
        Token::SeqEnd
    ]
);

Testing Deserialization

A Deserializer is constructed by providing a sequence of Tokens to be deserialized into a value. During testing, the claims crate can be used to assert that deserialization succeeds and returns the expected value.

use claims::assert_ok_eq;
use serde::Deserialize;
use serde_assert::{
    Deserializer,
    Token,
};

let mut deserializer = Deserializer::builder([Token::Bool(true)]).build();

assert_ok_eq!(bool::deserialize(&mut deserializer), true);

Testing Roundtrip

To assert that a value remains the same when serialized and then deserialized again, the output of the Serializer can be used as input to the Deserializer.

use claims::{
    assert_ok,
    assert_ok_eq,
};
use serde::{
    Deserialize,
    Serialize,
};
use serde_assert::{
    Deserializer,
    Serializer,
};

let value = true;

let serializer = Serializer::builder().build();
let mut deserializer = Deserializer::builder(assert_ok!(value.serialize(&serializer))).build();

assert_ok_eq!(bool::deserialize(&mut deserializer), value);

Modules

• de
  Testing deserialization implementations.
• ser
  Testing serialization implementations.
• token
  Tokens representing a serialized object.

Structs

• Deserializer
  Deserializer for testing Deserialize implementations.
• Serializer
  Serializer for testing Serialize implementations.

Enums

• Token
  A single serialized value.