# tmp_env

[![Version](https://img.shields.io/crates/v/tmp_env.svg)](https://crates.io/crates/tmp_env)
[![Documentation](https://docs.rs/tmp_env/badge.svg)](https://docs.rs/tmp_env)

tmp_env is a crate which lets you create temporary environment and be automatically cleaned when not needed.

For example sometimes you need to change the current directory or set environment variables to launch a process but you don't need this temporary environment for the rest of your program.
Then you will use `tmp_env` to create environment variable using `tmp_env::set_var` instead of `std::env::set_var` to get from `tmp_env::set_var` a datastructure which will automatically restore the
corresponding environment variable when dropped.

## Install

Put this dependency in your `Cargo.toml`

```toml
tmp_env = "0.1"
```

## Usage

- To temporary change the current directory:

```rust
{
    let _tmp_current_dir = tmp_env::set_current_dir("src").expect("should set the new current_dir");
    let current_dir = std::env::current_dir().expect("cannot get current dir from std env");
    assert!(current_dir.ends_with("src"));
}
let current_dir = std::env::current_dir().expect("cannot get current dir from std env");
assert!(!current_dir.ends_with("src"));
```

- To temporary set an environment variable:

```rust
{
    let _tmp_env = tmp_env::set_var("TEST_TMP_ENV", "myvalue");
    assert_eq!(std::env::var("TEST_TMP_ENV"), Ok(String::from("myvalue")));
}
// Because guard `_tmp_env` is dropped then the environment variable is also automatically unset (not restored because no previous value was set)
assert!(std::env::var("TEST_TMP_ENV").is_err());
```

- To temporary create a directory

```rust
{
    let tmp_dir = tmp_env::create_temp_dir().expect("cannot create temp dir"); // When tmp_dir is dropped this temporary dir will be removed
    assert!(std::fs::metadata(&*tmp_dir).is_ok());
}
// The temporary directory is now removed
```