# assert2
All-purpose [`assert!(...)`](https://docs.rs/assert2/latest/assert2/macro.assert.html) and [`check!(...)`](https://docs.rs/assert2/latest/assert2/macro.check.html) macros, inspired by [Catch2](https://github.com/catchorg/Catch2).
This crate is currently a work in progress.
It relies on a nightly compiler with the `proc_macro_span` features.
## Why these macros?
These macros offer some benefits over the assertions from the standard library:
* The macros parse your expression to detect comparisons and adjust the error message accordingly.
No more `assert_eq` or `assert_ne`, just write `assert!(1 + 1 == 2)`, or even `assert!(1 + 1 > 1)`!
* You can test for pattern matches: `assert!(let Err(_) = File::open("/non/existing/file"))`.
* The `check` macro can be used to perform multiple checks before panicking.
* The macros provide more information when the assertion fails.
* Colored failure messages!
The macros also accept additional arguments for a custom message, so it is fully comptabible with `std::assert`.
That means you don't have to worry about overwriting the standard `assert` with `use assert2::assert`.
## Examples
```rust
check!(6 + 1 <= 2 * 3);
```
----------
```rust
check!(true && false);
```
----------
```rust
check!(let Ok(_) = File::open("/non/existing/file"));
```
## `assert` vs `check`
The crate provides two macros: `check!(...)` and `assert!(...)`.
The main difference is that `check` doesn't immediately panic.
Instead, it will print the assertion error and fail the test.
This allows you to run multiple checks and can help to determine the reason of a test failure more easily.
Currently, `check` uses a scope guard to delay the panic until the current scope ends.
Ideally, `check` doesn't panic at all, but only signals that a test case has failed.
If this becomes possible in the future, the `check` macro will change, so **you should not rely on `check` to panic**.
## Controlling colored output.
You can force colored output on or off by setting the `CLICOLOR` environment variable.
Set `CLICOLOR=1` to forcibly enable colors, or `CLICOLORS=0` to disable them.
If the environment variable is unset or set to `auto`, output will be colored if it is going to a terminal.