#assert #diff #pretty #color

dev pretty_assertions

Overwrite assert_eq! and assert_ne! with drop-in replacements, adding colorful diffs

16 releases

✓ Uses Rust 2018 edition

0.6.1 Feb 21, 2019
0.5.1 Mar 4, 2018
0.4.1 Dec 10, 2017
0.4.0 Oct 15, 2017
0.1.2 Mar 29, 2017

#2 in Development tools

Download history 8614/week @ 2018-11-08 8651/week @ 2018-11-15 8729/week @ 2018-11-22 10315/week @ 2018-11-29 9653/week @ 2018-12-06 9744/week @ 2018-12-13 7436/week @ 2018-12-20 220/week @ 2018-12-27 8460/week @ 2019-01-03 8186/week @ 2019-01-10 8181/week @ 2019-01-17 9029/week @ 2019-01-24 11141/week @ 2019-01-31 14931/week @ 2019-02-07 12629/week @ 2019-02-14

41,475 downloads per month
Used in 136 crates (134 directly)

MIT/Apache

62KB
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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};
Show the example behind the screenshots above.
// 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.

Dependencies

~797KB