rust-pretty-assertions

Overwrite `assert_eq!` with a drop-in replacement, adding a colorful diff.

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Pretty Assertions

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

Wouldn't that task be much easier with a colorful diff?

pretty assertion

Yep — and you only need one line of code to make it happen:

use pretty_assertions::{assert_eq, assert_ne};
// 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);
}

Tip

Specify it as [dev-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:

#[cfg(test)]
use pretty_assertions::{assert_eq, assert_ne};

Note

  • 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.

License

Licensed under either of

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.

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概览
名称与所有者rust-pretty-assertions/rust-pretty-assertions
主编程语言Rust
编程语言Rust (语言数: 3)
平台
许可证Apache License 2.0
所有者活动
创建于2017-03-27 07:12:15
推送于2025-09-27 05:37:40
最后一次提交
发布数26
最新版本名称v1.4.1 (发布于 2024-09-15 21:07:26)
第一版名称v0.1.0 (发布于 2017-03-27 07:33:05)
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