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# Fixture-based test framework for Rust

## Introduction

`rstest` uses procedural macros to help you on writing
fixtures and table-based tests. To use it, add the
following lines to your `Cargo.toml` file:

```toml
[dev-dependencies]
rstest = "0.26.1"
```

### Features

- `async-timeout`: `timeout` for `async` tests (Default enabled)
- `crate-name`: Import `rstest` package with different name (Default enabled)

### Fixture

The core idea is that you can inject your test dependencies
by passing them as test arguments. In the following example,
a `fixture` is defined and then used in two tests,
simply providing it as an argument:

```rust
use rstest::*;

#[fixture]
pub fn fixture() -> u32 { 42 }

#[rstest]
fn should_success(fixture: u32) {
    assert_eq!(fixture, 42);
}

#[rstest]
fn should_fail(fixture: u32) {
    assert_ne!(fixture, 42);
}
```

### Parametrize

You can also inject values in some other ways. For instance, you can
create a set of tests by simply providing the injected values for each
case: `rstest` will generate an independent test for each case.

```rust
use rstest::rstest;

#[rstest]
#[case(0, 0)]
#[case(1, 1)]
#[case(2, 1)]
#[case(3, 2)]
#[case(4, 3)]
fn fibonacci_test(#[case] input: u32, #[case] expected: u32) {
    assert_eq!(expected, fibonacci(input))
}
```

Running `cargo test` in this case executes five tests:

```bash
running 5 tests
test fibonacci_test::case_1 ... ok
test fibonacci_test::case_2 ... ok
test fibonacci_test::case_3 ... ok
test fibonacci_test::case_4 ... ok
test fibonacci_test::case_5 ... ok

test result: ok. 5 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out
```

If you need to just providing a bunch of values for which you
need to run your test, you can use `#[values(list, of, values)]`
argument attribute:

```rust
use rstest::rstest;

#[rstest]
fn should_be_invalid(
    #[values(None, Some(""), Some("    "))]
    value: Option<&str>
) {
    assert!(!valid(value))
}
```

Or create a _matrix_ test by using _list of values_ for some
variables that will generate the cartesian product of all the
values.

#### Use Parametrize definition in more tests

If you need to use a test list for more than one test you can use [`rstest_reuse`][reuse-crate-link]
crate. With this helper crate you can define a template and use it everywhere.

```rust
use rstest::rstest;
use rstest_reuse::{self, *};

#[template]
#[rstest]
#[case(2, 2)]
#[case(4/2, 2)]
fn two_simple_cases(#[case] a: u32, #[case] b: u32) {}

#[apply(two_simple_cases)]
fn it_works(#[case] a: u32, #[case] b: u32) {
    assert!(a == b);
}
```

See [`rstest_reuse`][reuse-crate-link] for more details.

#### Feature flagged cases

In case you want certain test cases to only be present if a certain feature is
enabled, use `#[cfg_attr(feature = …, case(…))]`:

```rust
use rstest::rstest;

#[rstest]
#[case(2, 2)]
#[cfg_attr(feature = "frac", case(4/2, 2))]
fn it_works(#[case] a: u32, #[case] b: u32) {
    assert!(a == b);
}
```

This also works with [`rstest_reuse`][reuse-crate-link].

### Magic Conversion

If you need a value where its type implement `FromStr()` trait you can use a literal
string to build it:

```rust
# use rstest::rstest;
# use std::net::SocketAddr;
#[rstest]
#[case("1.2.3.4:8080", 8080)]
#[case("127.0.0.1:9000", 9000)]
fn check_port(#[case] addr: SocketAddr, #[case] expected: u16) {
    assert_eq!(expected, addr.port());
}
```

You can use this feature also in value list and in fixture default value.

### Async

`rstest` supports async tests, but makes no assumptions about what
async runtime you are using. Async tests require either an
[explicit test attribute](#explicit-test-attribute) or an
[implicit test attribute](#implicit-test-attribute).

You are responsible for providing any appropriate peer dependencies to run your async tests.

If your test input is an async value (fixture or test parameter) you can use `#[future]`
attribute to remove `impl Future<Output = T>` boilerplate and just use `T`:

```rust
use rstest::*;
#[fixture]
async fn base() -> u32 { 42 }

#[rstest]
#[tokio::test]
#[case(21, async { 2 })]
#[case(6, async { 7 })]
async fn my_async_test(
    #[future] base: u32,
    #[case] expected: u32,
    #[future] #[case] div: u32
) {
    assert_eq!(expected, base.await / div.await);
}
```

As you noted you should `.await` all _future_ values and this sometimes can be really boring.
In this case you can use `#[future(awt)]` to _awaiting_ an input or annotating your function
with `#[awt]` attributes to globally `.await` all your _future_ inputs. Previous code can be
simplified as follows:

```rust
use rstest::*;
# #[fixture]
# async fn base() -> u32 { 42 }
#[rstest]
#[tokio::test]
#[case(21, async { 2 })]
#[case(6, async { 7 })]
#[awt]
async fn global(
    #[future] base: u32,
    #[case] expected: u32,
    #[future] #[case] div: u32
) {
    assert_eq!(expected, base / div);
}

#[rstest]
#[tokio::test]
#[case(21, async { 2 })]
#[case(6, async { 7 })]
async fn single(
    #[future] base: u32,
    #[case] expected: u32,
    #[future(awt)] #[case] div: u32
) {
    assert_eq!(expected, base.await / div);
}
```

### Files path as input arguments

If you need to create a test for each file in a given location you can use
`#[files("glob path syntax")]` attribute to generate a test for each file that
satisfy the given glob path.

```rust
#[rstest]
fn for_each_file(
    #[files("src/**/*.rs")]
    #[exclude("test")] path: PathBuf
) {
    assert!(check_file(&path))
}
```

The default behavior is to ignore the files that start with `"."`, but you can
modify this by use `#[include_dot_files]` attribute. The `files` attribute can be
used more than once on the same variable, and you can also create some custom
exclusion rules with the `#[exclude("regex")]` attributes that filter out all
paths that verify the regular expression.

You can pass in environment variables by using `${ENV_VAR_NAME}` in the glob
path, e.g. `#[files("${SOME_ENV}/hello")]`. To set a default value for the
environment variable, use `${ENV_VAR_NAME:-default_value}`.

Files are resolved at compile time against your Cargo project root
(the `CARGO_MANIFEST_DIR` environment variable). If you need to change this
behavior, you can use the `#[base_dir = "..."]` attribute to specify a different
base directory. That directory MUST exist, and will be used as the root for
the files, as well as to resolve the relative path when creating the test name.
Similar to the `files` attribute, you can use `${ENV_VAR_NAME}` in the `base_dir`.

The `#[files(...)]` attribute ignores matched directory paths by default,
returning only file paths. If you need the test cases to include directories
found by the glob pattern, use the `#[dirs]` attribute in conjunction with `#[files(...)]`.

### Use `#[once]` Fixture

If you need to a fixture that should be initialized just once for all tests
you can use `#[once]` attribute. `rstest` call your fixture function just once and
return a reference to your function result to all your tests:

```rust
#[fixture]
#[once]
fn once_fixture() -> i32 { 42 }

#[rstest]
fn single(once_fixture: &i32) {
    // All tests that use once_fixture will share the same reference to once_fixture()
    // function result.
    assert_eq!(&42, once_fixture)
}
```

### Test `#[timeout()]`

You can define an execution timeout for your tests with `#[timeout(<duration>)]` attribute. Timeout
works both for sync and async tests and is runtime agnostic. `#[timeout(<duration>)]` take an
expression that should return a `std::time::Duration`. Follow a simple async example:

```rust
use rstest::*;
use std::time::Duration;

async fn delayed_sum(a: u32, b: u32, delay: Duration) -> u32 {
    async_std::task::sleep(delay).await;
    a + b
}

#[rstest]
#[async_std::test]
#[timeout(Duration::from_millis(80))]
async fn single_pass() {
    assert_eq!(4, delayed_sum(2, 2, ms(10)).await);
}
```

In this case test pass because the delay is just 10 milliseconds and timeout is
80 milliseconds.

You can use `timeout` attribute like any other attribute in your tests, and you can
override a group timeout with a case specific one. In the follow example we have
3 tests where first and third use 100 milliseconds but the second one use 10 milliseconds.
Another valuable point in this example is to use an expression to compute the
duration.

```rust
fn ms(ms: u32) -> Duration {
    Duration::from_millis(ms.into())
}

#[rstest]
#[case::pass(ms(1), 4)]
#[timeout(ms(10))]
#[case::fail_timeout(ms(60), 4)]
#[case::fail_value(ms(1), 5)]
#[timeout(ms(100))]
async fn group_one_timeout_override(#[case] delay: Duration, #[case] expected: u32) {
    assert_eq!(expected, delayed_sum(2, 2, delay).await);
}
```

If you want to use `timeout` for `async` test you need to use `async-timeout`
feature (enabled by default).

### Default timeout

You can set a default timeout for test using the `RSTEST_TIMEOUT` environment variable.
The value is in seconds and is evaluated on test compile time.

### Explicit Test Attribute

If your test contains an attribute `#[test_attr(...)]`, this is an explicit test attribute declaration.
The contents of the parentheses will be inserted as an attribute of your test. This allows for arbitrary
test attribute syntax.

For instance, if you want to test an async function with [`smol_macros::test`](https://docs.rs/smol-macros/0.1.1/smol_macros/macro.test.html),
you can write

```rust
use rstest::*;
use macro_rules_attribute::apply;
use smol_macros::test;
use std::future::Future;

#[rstest]
#[case(2, async { 4 })]
#[case(21, async { 42 })]
#[test_attr(apply(test))]
async fn my_async_test(#[case] a: u32, #[case] #[future] result: u32) {
    assert_eq!(2 * a, result.await);
}
```

When using an explicit test attribute, ensure it appears after any `#[case()]` attributes so that the attribute binds
to the test function and not the case.

### Implicit Test Attribute

If your test contains an attribute whose path ends in `test`, this is treated
as an implicit test attribute, and replaces the default `#[test]` attribute.
Simply including the attribute in your test's attribute list is all that is required.

For instance, if you want to test an async function with the `actix_rt::test` attribute, you can just write:

```rust
use rstest::*;
use actix_rt;
use std::future::Future;

#[rstest]
#[case(2, async { 4 })]
#[case(21, async { 42 })]
#[actix_rt::test]
async fn my_async_test(#[case] a: u32, #[case] #[future] result: u32) {
    assert_eq!(2 * a, result.await);
}
```

Implicit test attributes have a lower priority than [`explicit test attributes`](#explicit-test-attribute).
If you have an unrelated attribute whose path ends in `test`, you should declare an explicit test attribute
for deconfliction.

When using an implicit test attribute, ensure it appears after any `#[case()]` attributes so that the attribute binds to the
test function and not the case.

### Default Test Attribute

Synchronous tests use `#[test]` as the default test attribute if nothing else is supplied explicitly or implicitly.

Asynchronous tests will fail to compile if no test attribute is specified explicitly or implicitly.

## Test `Context` object

You can have a [`Context`] object for your test just by annotate an argument by `#[context]` attribute.
This object contains some useful information both to implement simple logics and debugging stuff.

```rust
use rstest::{rstest, Context};

#[rstest]
#[case::a_description(42)]
fn my_test(#[context] ctx: Context, #[case] _c: u32) {
    assert_eq!("my_test", ctx.name);
    assert_eq!(Some("a_description"), ctx.description);
    assert_eq!(Some(0), ctx.case);

    std::thread::sleep(std::time::Duration::from_millis(100));
    assert!(ctx.start.elapsed() >= std::time::Duration::from_millis(100));
}
```

## Local lifetime and `#[by_ref]` attribute

In some cases you may want to use a local lifetime for some arguments of your test.
In these cases you can use the `#[by_ref]` attribute then use the reference instead
the value.

```rust
enum E<'a> {
    A(bool),
    B(&'a Cell<E<'a>>),
}

fn make_e_from_bool<'a>(_bump: &'a (), b: bool) -> E<'a> {
    E::A(b)
}

#[fixture]
fn bump() -> () {}

#[rstest]
#[case(true, E::A(true))]
fn it_works<'a>(#[by_ref] bump: &'a (), #[case] b: bool, #[case] expected: E<'a>) {
    let actual = make_e_from_bool(&bump, b);
    assert_eq!(actual, expected);
}
```

You can use `#[by_ref]` attribute for all arguments of your test and not just for fixture
but also for cases, values and files.

## Complete Example

All these features can be used together with a mixture of fixture variables,
fixed cases and a bunch of values. For instance, you might need two
test cases which test for panics, one for a logged-in user and one for a guest user.

```rust
use rstest::*;

#[fixture]
fn repository() -> InMemoryRepository {
    let mut r = InMemoryRepository::default();
    // fill repository with some data
    r
}

#[fixture]
fn alice() -> User {
    User::logged("Alice", "2001-10-04", "London", "UK")
}

#[rstest]
#[case::authorized_user(alice())] // We can use `fixture` also as standard function
#[case::guest(User::Guest)]   // We can give a name to every case : `guest` in this case
// and `authorized_user`
#[should_panic(expected = "Invalid query error")] // We would test a panic
fn should_be_invalid_query_error(
    repository: impl Repository,
    #[case] user: User,
    #[values("     ", "^%$some#@invalid!chars", ".n.o.d.o.t.s.")] query: &str,
) {
    repository.find_items(&user, query).unwrap();
}
```

This example will generate exactly 6 tests grouped by 2 different cases:

```text
running 6 tests
test should_be_invalid_query_error::case_1_authorized_user::query_1_____ - should panic ... ok
test should_be_invalid_query_error::case_2_guest::query_2_____someinvalid_chars__ - should panic ... ok
test should_be_invalid_query_error::case_1_authorized_user::query_2_____someinvalid_chars__ - should panic ... ok
test should_be_invalid_query_error::case_2_guest::query_3____n_o_d_o_t_s___ - should panic ... ok
test should_be_invalid_query_error::case_1_authorized_user::query_3____n_o_d_o_t_s___ - should panic ... ok
test should_be_invalid_query_error::case_2_guest::query_1_____ - should panic ... ok

test result: ok. 6 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s
```

Note that the names of the values _try_ to convert the input expression in a
Rust valid identifier name to help you find which tests fail.

## More

Is that all? Not quite yet!

A fixture can be injected by another fixture, and they can be called
using just some of its arguments.

```rust
#[fixture]
fn user(#[default("Alice")] name: &str, #[default(22)] age: u8) -> User {
    User::new(name, age)
}

#[rstest]
fn is_alice(user: User) {
    assert_eq!(user.name(), "Alice")
}

#[rstest]
fn is_22(user: User) {
    assert_eq!(user.age(), 22)
}

#[rstest]
fn is_bob(#[with("Bob")] user: User) {
    assert_eq!(user.name(), "Bob")
}

#[rstest]
fn is_42(#[with("", 42)] user: User) {
    assert_eq!(user.age(), 42)
}
```

As you noted you can provide default values without the need of a fixture
to define it.

Finally, if you need tracing the input values you can just
add the `trace` attribute to your test to enable the dump of all input
variables.

```rust
#[rstest]
#[case(42, "FortyTwo", ("minus twelve", -12))]
#[case(24, "TwentyFour", ("minus twentyfour", -24))]
#[trace] //This attribute enable tracing
fn should_fail(#[case] number: u32, #[case] name: &str, #[case] tuple: (&str, i32)) {
    assert!(false); // <- stdout come out just for failed tests
}
```

```text
running 2 tests
test should_fail::case_1 ... FAILED
test should_fail::case_2 ... FAILED

failures:

---- should_fail::case_1 stdout ----
------------ TEST ARGUMENTS ------------
number = 42
name = "FortyTwo"
tuple = ("minus twelve", -12)
-------------- TEST START --------------
thread 'should_fail::case_1' panicked at 'assertion failed: false', src/main.rs:64:5
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace.

---- should_fail::case_2 stdout ----
------------ TEST ARGUMENTS ------------
number = 24
name = "TwentyFour"
tuple = ("minus twentyfour", -24)
-------------- TEST START --------------
thread 'should_fail::case_2' panicked at 'assertion failed: false', src/main.rs:64:5


failures:
    should_fail::case_1
    should_fail::case_2

test result: FAILED. 0 passed; 2 failed; 0 ignored; 0 measured; 0 filtered out
```

In case one or more variables don't implement the `Debug` trait, an error
is raised, but it's also possible to exclude a variable using the
`#[notrace]` argument attribute.

You can learn more on [Docs][docs-link] and find more examples in
[`tests/resources`](/rstest/tests/resources) directory.

## Changelog

See [CHANGELOG.md](/CHANGELOG.md)

## License

Licensed under either of

* Apache License, Version 2.0, ([LICENSE-APACHE](/LICENSE-APACHE) or
  [license-apache-link])

* MIT license [LICENSE-MIT](/LICENSE-MIT) or [license-MIT-link]
  at your option.

[//]: # (links)

[crate-image]: https://img.shields.io/crates/v/rstest.svg

[crate-link]: https://crates.io/crates/rstest

[docs-image]: https://docs.rs/rstest/badge.svg

[docs-link]: https://docs.rs/rstest/

[test-action-image]: https://github.com/la10736/rstest/workflows/Test/badge.svg

[test-action-link]: https://github.com/la10736/rstest/actions?query=workflow:Test

[license-apache-image]: https://img.shields.io/badge/license-Apache2.0-blue.svg

[license-mit-image]: https://img.shields.io/badge/license-MIT-blue.svg

[license-apache-link]: http://www.apache.org/licenses/LICENSE-2.0

[license-MIT-link]: http://opensource.org/licenses/MIT

[reuse-crate-link]: https://crates.io/crates/rstest_reuse
