# Pretty Assertions [![Latest version](https://img.shields.io/crates/v/pretty-assertions.svg)](https://crates.io/crates/pretty-assertions) [![docs.rs](https://img.shields.io/docsrs/pretty_assertions)](https://docs.rs/pretty_assertions) [![Downloads of latest version](https://img.shields.io/crates/dv/pretty-assertions.svg)](https://crates.io/crates/pretty-assertions) [![All downloads](https://img.shields.io/crates/d/pretty-assertions.svg)](https://crates.io/crates/pretty-assertions) Overwrite `assert_eq!` with a drop-in replacement, adding a colorful diff. ## Usage When writing tests in Rust, you'll probably use `assert_eq!(a, b)` _a lot_. If such a test fails, it will present all the details of `a` and `b`. But you have to spot the differences yourself, which is not always straightforward, like here: ![standard assertion](https://raw.githubusercontent.com/rust-pretty-assertions/rust-pretty-assertions/2d2357ff56d22c51a86b2f1cfe6efcee9f5a8081/examples/standard_assertion.png) Wouldn't that task be _much_ easier with a colorful diff? ![pretty assertion](https://raw.githubusercontent.com/rust-pretty-assertions/rust-pretty-assertions/2d2357ff56d22c51a86b2f1cfe6efcee9f5a8081/examples/pretty_assertion.png) Yep — and you only need **one line of code** to make it happen: ```rust,ignore use pretty_assertions::{assert_eq, assert_ne}; ``` <details> <summary>Show the example behind the screenshots above.</summary> ```rust,ignore // 1. add the `pretty_assertions` dependency to `Cargo.toml`. // 2. insert this line at the top of each module, as needed use pretty_assertions::{assert_eq, assert_ne}; fn main() { #[derive(Debug, PartialEq)] struct Foo { lorem: &'static str, ipsum: u32, dolor: Result<String, String>, } let x = Some(Foo { lorem: "Hello World!", ipsum: 42, dolor: Ok("hey".to_string())}); let y = Some(Foo { lorem: "Hello Wrold!", ipsum: 42, dolor: Ok("hey ho!".to_string())}); assert_eq!(x, y); } ``` </details> ## Semantic Versioning The exact output of assertions is **not guaranteed** to be consistent over time, and may change between minor versions. The output of this crate is designed to be read by a human. It is not suitable for exact comparison, for example in snapshot testing. This crate adheres to semantic versioning for publically exported crate items, **except** the `private` module, which may change between any version. ## Tip Specify it as [`[dev-dependencies]`](http://doc.crates.io/specifying-dependencies.html#development-dependencies) and it will only be used for compiling tests, examples, and benchmarks. This way the compile time of `cargo build` won't be affected! Also add `#[cfg(test)]` to your `use` statements, like this: ```rust,ignore #[cfg(test)] use pretty_assertions::{assert_eq, assert_ne}; ``` ## Notes - Since `Rust 2018` edition, you need to declare `use pretty_assertions::{assert_eq, assert_ne};` per module. Before you would write `#[macro_use] extern crate pretty_assertions;`. - The replacement is only effective in your own crate, not in other libraries you include. - `assert_ne` is also switched to multi-line presentation, but does _not_ show a diff. - Under Windows, the terminal state is modified to properly handle VT100 escape sequences, which may break display for certain use cases. - The minimum supported rust version (MSRV) is 1.35.0 ### `no_std` support For `no_std` support, disable the `std` feature and enable the `alloc` feature: ```toml # Cargo.toml pretty_assertions = { version= "...", default-features = false, features = ["alloc"] } ``` ## License Licensed under either of - Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or <http://www.apache.org/licenses/LICENSE-2.0>) - MIT license ([LICENSE-MIT](LICENSE-MIT) or <http://opensource.org/licenses/MIT>) at your option. ### Contribution Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions. ## Development - Cut a new release by creating a GitHub release with tag. Crate will be built and uploaded to crates.io by GHA.