Crate pretty_assertions [−] [src]
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 #[macro_use] 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; 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); }
Macros
assert_eq |