temp-env 0.2.0

Set environment variables temporarily.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74

temp-env
========

Set environment variables temporarily.

This crate is useful for testing with different environment variables that should not interfere.

This code started as a small test helper written by [@fabian-braun] and [@nbaztec] and published by [@fabian-braun]
on [StackOverflow]. [@vmx] found it useful and took the time to make it a proper crate.

Example
-------

```rust
temp_env::with_var("MY_ENV_VAR", Some("production"), || {
    // Run some code where `MY_ENV_VAR` set to `"production"`.
});


temp_env::with_vars(
    vec![
        ("FIRST_VAR", Some("Hello")),
        ("SECOND_VAR", Some("World!")),
    ],
    || {
        // Run some code where `FIRST_VAR` is set to `"Hello"` and `SECOND_VAR` is set to
        // `"World!"`.
    }
);

temp_env::with_vars(
    vec![
        ("FIRST_VAR", Some("Hello")),
        ("SECOND_VAR", None),
    ],
    || {
        // Run some code where `FIRST_VAR` is set to `"Hello"` and `SECOND_VAR` is unset (even if
        // it was set before)
    }
);
```

How does it work?
-------

This crate sets and unsets environment variables for the currently running (Rust) process. 
It leverages [`std::env::set_var`].

The provided functions `temp_env::with_*` provide the following features:
- Avoid interference when running concurrently
- Reset previously set env variables back to their original value upon completion, also in case of panic
- Temporarily unsetting env variables

Note that the crate makes use of a singleton mutex to avoid side effects between concurrently running tests.
This may impact the degree of concurrency in your test execution.

License
-------

This project is licensed under either of

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

at your option.


[StackOverflow]: https://stackoverflow.com/questions/35858323/how-can-i-test-rust-methods-that-depend-on-environment-variables/67433684#67433684
[@fabian-braun]: https://github.com/fabian-braun
[@nbaztec]: https://github.com/nbaztec
[@vmx]: https://github.com/vmx
[LICENSE-APACHE]: LICENSE-APACHE
[LICENSE-MIT]: LICENSE-MIT
[`std::env::set_var`]: https://doc.rust-lang.org/std/env/fn.set_var.html