# snaptest

[![CircleCI branch](https://img.shields.io/circleci/project/github/zacharygolba/snaptest/master.svg?style=flat-square)](https://circleci.com/gh/zacharygolba/snaptest/tree/master) [![AppVeyor branch](https://img.shields.io/appveyor/ci/zacharygolba/snaptest/master.svg?logo=appveyor&style=flat-square)](https://ci.appveyor.com/project/zacharygolba/snaptest/branch/master) [![Crates.io](https://img.shields.io/crates/v/snaptest.svg?style=flat-square)](https://crates.io/crates/snaptest)

Dead simple snapshot testing (inspired by [jest](https://facebook.github.io/jest/)).

Documentation (including this README) is a work in progress. Feel free to submit an issue if you have a question about usage.

## Features

- Any type that implements [`Debug`](https://doc.rust-lang.org/std/fmt/trait.Debug.html) can be returned from a test.
- First class integration with [`failure`](https://boats.gitlab.io/failure/).
- The snapshot store is thread safe so your tests can run in parallel.
- Beautiful diffs are printed when a snapshot test fails.
- A single small binary file is used to store snapshots.

TODO

## Installation

First, add `snaptest` to the dependencies section of your `Cargo.toml`:

```toml
[dependencies]
snaptest = "0.1"
```

Next, add the following snippet to the entry point of your crate (`lib.rs` or `main.rs`):

```rust
#[macro_use]
extern crate snaptest;
```

## Usage

Derive `Debug` on types that you want to use with snaptest:

```rust
use std::str::FromStr;

#[derive(Debug)]
pub struct User {
    connection: Connection,
    name: String,
}

#[derive(Debug)]
pub enum Connection {
    Online,
    Offline,
}

impl FromStr for User {
  // ...
}
```

Now, in the test module for the `User` struct:

```rust
snaptest!{
    fn parse_user() -> Result<User, Error> {
        "Zak:online".parse()
    }
}
```

Next time your test runs, a snapshot will be added to a local `.snapfile` to compare against future test results. If you get a different result back than what matches the snapshot, the test will fail and the diff will be printed to the console.

![Snaptest Example](./docs/example.png)

## License

Licensed under either of

* Apache License, Version 2.0
  ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
* MIT license
  ([LICENSE-MIT](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.