# power-assert-rs

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Power Assert in Rust. Provides better assertion message like this:

```
$ cargo run --example normal
     Running `target/debug/examples/normal`
thread '<main>' panicked at 'assertion failed: bar.val == bar.foo.val
power_assert!(bar.val == bar.foo.val)
              |   |   |  |   |   |
              |   3   |  |   |   2
              |       |  |   Foo { val: 2 }
              |       |  Bar { val: 3, foo: Foo { val: 2 } }
              |       false
              Bar { val: 3, foo: Foo { val: 2 } }
', examples/normal.rs:26
An unknown error occurred

To learn more, run the command again with --verbose.
```

# How to use

Add this to your `Cargo.toml`:

```toml
[dependencies]
power-assert = "*"
```

and add this to your `lib.rs` or `main.rs`:

```rust
#![feature(plugin)]
#![plugin(power_assert)]
```

Now, you can use `power_assert!()` and `power_assert_eq!()`.

If you want to override builtin `assert!()` and `assert_eq!()`, change your `lib.rs` or `main.rs` as follows.

```rust
#![feature(plugin)]
#![plugin(power_assert(override_builtins))]
```