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, ], ); }