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:
Wouldn't that task be much easier with a colorful diff?
Yes it would. And you only need one line of code to make it happen — seriously:
// add the following line to the top of your crate root to
// overwrite `assert_eq!` with a colorful drop-in replacement
extern crate pretty_assertions;
Ok, and don't forget to add the pretty_assertions
dependency to Cargo.toml
.
Does that count as a line of code?.. ;-)
Note
pretty_assertions
is an ultra-thin wrapper around thedifference
crate, which does the heavy lifting. It replaces theassert_eq!
macro with just about 22 lines of code.- The replacement is only effective in your own crate, not in other libraries you include.
Example
This is the Rust code behind the screenshots above.
// uncomment the next line to make the assertions colorful:
//#[macro_use] extern crate pretty_assertions;
License
Licensed under either of
- Apache License, Version 2.0, (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
- MIT license (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.