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https://github.com/la10736/rstest

Fixture-based test framework for Rust
https://github.com/la10736/rstest

rust test-framework testing testing-tools

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Fixture-based test framework for Rust

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[![Crate][crate-image]][crate-link]

[![Docs][docs-image]][docs-link]

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[![MIT Licensed][license-mit-image]][license-mit-link]



# 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 = "0.23.0"

```



### 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))]

#[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` provides out of the box `async` support. Just mark your

test function as `async`, and it'll use `#[async-std::test]` to

annotate it. This feature can be really useful to build async

parametric tests using a tidy syntax:



```rust

use rstest::*;



#[rstest]

#[case(5, 2, 3)]

#[should_panic]

#[case(42, 40, 1)]

async fn my_async_test(#[case] expected: u32, #[case] a: u32, #[case] b: u32) {

    assert_eq!(expected, async_sum(a, b).await);

}

```



Currently, only `async-std` is supported out of the box. But if you need to use

another runtime that provide its own test attribute (i.e. `tokio::test` or

`actix_rt::test`) you can use it in your `async` test like described in

[Inject Test Attribute](#inject-test-attribute).



To use this feature, you need to enable `attributes` in the `async-std`

features list in your `Cargo.toml`:



```toml

async-std = { version = "1.13", features = ["attributes"] }

```



If your test input is an async value (fixture or test parameter) you can use `#[future]`

attribute to remove `impl Future` boilerplate and just use `T`:



```rust

use rstest::*;

#[fixture]

async fn base() -> u32 { 42 }



#[rstest]

#[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 like follow:



```rust

use rstest::*;

# #[fixture]

# async fn base() -> u32 { 42 }

#[rstest]

#[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]

#[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`.



### 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.



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



You can define an execution timeout for your tests with `#[timeout()]` attribute. Timeout

works both for sync and async tests and is runtime agnostic. `#[timeout()]` 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]

#[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).



### Inject Test Attribute



If you would like to use another `test` attribute for your test you can simply

indicate it in your test function's attributes. For instance if you want

to test some async function with use `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);

}

```



Just the attributes that ends with `test` (last path segment) can be injected.



### 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)

}

```



## 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>),

}



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.



## Rust version compatibility



The minimum supported Rust version is 1.67.1.



## 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