https://github.com/oknozor/sealed-test
A procmacro attribute to run your test in an isolated environment
https://github.com/oknozor/sealed-test
Last synced: 5 months ago
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A procmacro attribute to run your test in an isolated environment
- Host: GitHub
- URL: https://github.com/oknozor/sealed-test
- Owner: oknozor
- License: mit
- Created: 2021-12-07T15:52:26.000Z (over 3 years ago)
- Default Branch: main
- Last Pushed: 2024-05-28T14:02:36.000Z (11 months ago)
- Last Synced: 2024-05-29T19:28:15.193Z (11 months ago)
- Language: Rust
- Size: 21.5 KB
- Stars: 24
- Watchers: 3
- Forks: 2
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
## Sealed test
This crate exposes the `#[sealed_test]` macro attribute to run your tests in an isolated environment.
It provides the following :
- an isolated process using [rusty-fork](https://crates.io/crates/two-rusty-forks)
- a temporary work dir with [tempfile](https://crates.io/crates/tempfile).
- a set of handy attributes to configure your tests including:
- `before`/`after`: setup and teardown functions for your tests.
- `env`: set environment variables in the test process.
- `files`: copy files from your crate directory to the test temporary directory.
**Caution:** using `#[sealed_test]` instead of `#[test]` will create a temporary file
and set it to be the test current directory but, nothing stops you from changing that directory
using `std::env::set_current_dir`.
### Why ?
If you run `cargo test` your tests will run in parallel, in some case this could be problematic.
Let us examine a concrete example.
```rust
#[test]
fn foo() -> Result<(), VarError> {
std::env::set_var("VAR", "foo");
let var = std::env::var("VAR")?;
assert_eq!(var, "foo");
Ok(())
}
#[test]
fn bar() -> Result<(), VarError> {
std::env::set_var("VAR", "bar");
// During the thread sleep, the `foo` test will run
// and set the environment variable to "foo"
std::thread::sleep(Duration::from_secs(1));
let var = std::env::var("VAR")?;
// If running tests on multiple threads the below assertion will fail
assert_eq!(var, "bar");
Ok(())
}
```
### With `sealed_test`
Here each test has its own environment, the tests will always pass !
```rust
use sealed_test::prelude::*;
#[sealed_test]
fn foo() -> Result<(), VarError> {
std::env::set_var("VAR", "bar");
let var = std::env::var("VAR")?;
assert_eq!(var, "bar");
Ok(())
}
#[sealed_test]
fn bar() -> Result<(), VarError> {
std::env::set_var("VAR", "bar");
std::thread::sleep(Duration::from_secs(1));
let var = std::env::var("VAR")?;
assert_eq!(var, "bar");
Ok(())
}
```
## Examples
### The `env` attribute
The `env` attribute allow to quickly set environment variable in your tests.
This is only syntactic sugar and you can still normally manipulate environment variables with `std::env`.
```rust
#[sealed_test(env = [ ("FOO", "foo"), ("BAR", "bar") ])]
fn should_set_env() {
let foo = std::env::var("FOO").expect("Failed to get $FOO");
let bar = std::env::var("BAR").expect("Failed to get $BAR");
assert_eq!(foo, "foo");
assert_eq!(bar, "bar");
}
```
**Tip**: Sealed tests have their own environment and variable from the parent
won't be affected by whatever you do with the test environment.
### The `files` attribute
If you need test behaviors that mutate the file system, you can use the `files`
attribute to quickly copy files from your crate root to the test working directory.
The test working directory lives in tmpfs and will be cleaned up after the test execution.
```rust
#[sealed_test(files = ["tests/foo", "tests/bar"])]
fn should_copy_files() {
assert!(PathBuf::from("foo").exists());
assert!(PathBuf::from("bar").exists());
}
```
### Setup and teardown
Use `before` and `after` to run a rust expression around your tests, typically a function, for instance `setup = setup_function()`.
#### `before` and `after`
```rust
#[sealed_test(before = setup(), after = teardown())]
fn should_run_setup_and_tear_down() {
// ...
}
fn setup() {
println!("Hello from setup")
}
fn teardown() {
println!("Hello from teardown")
}
```