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:
[dev-dependencies]
rstest = "0.13.0"
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::*;
pub fn fixture() -> u32 { 42 }
fn shouldsuccess(fixture: u32) { asserteq!(fixture, 42); }
fn shouldfail(fixture: u32) { assertne!(fixture, 42); } ```
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;
fn fibonaccitest(#[case] input: u32, #[case] expected: u32) { asserteq!(expected, fibonacci(input)) } ```
Running cargo test in this case executes five tests:
```bash running 5 tests test fibonaccitest::case1 ... ok test fibonaccitest::case2 ... ok test fibonaccitest::case3 ... ok test fibonaccitest::case4 ... ok test fibonaccitest::case5 ... 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;
fn shouldbeinvalid( #[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.
If you need to use a test list for more than one test you can use rstest_reuse
crate. With this helper crate you can define a template and use it everywhere .
```rust use rstest::rstest; use rstest_reuse::{self, *};
fn twosimplecases(#[case] a: u32, #[case] b: u32) {}
fn it_works(#[case] a: u32, #[case] b: u32) { assert!(a == b); } ```
See rstest_reuse for more dettails.
If you need a value where its type implement FromStr() trait you can use a literal
string to build it:
```rust
fn checkport(#[case] addr: SocketAddr, #[case] expected: u16) { asserteq!(expected, addr.port()); } ``` You can use this feature also in value list and in fixture default value.
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::*;
async fn myasynctest(#[case] expected: u32, #[case] a: u32, #[case] b: u32) {
asserteq!(expected, asyncsum(a, b).await);
}
``
Currently onlyasync-stdis supported out of the box. But if you need to use
another runtime that provide it's own test attribute (i.e.tokio::testor
actix_rt::test) you can use it in yourasync` test like described in
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 = "1.5", features = ["attributes"] }
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::*;
async fn base() -> u32 { 42 }
async fn myasynctest(#[future] base: u32, #[case] expected: u32, #[future] #[case] div: u32) { assert_eq!(expected, base.await / div.await); } ```
#[timeout()]You can define an execution timeout for your tests with #[timeout(<duration>)] attribute. Timeouts
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 delayedsum(a: u32, b: u32,delay: Duration) -> u32 { asyncstd::task::sleep(delay).await; a + b }
async fn singlepass() { asserteq!(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 attibute 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 millis but the second one use 10 millis.
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()) }
async fn grouponetimeoutoverride(#[case] delay: Duration, #[case] expected: u32) { asserteq!(expected, delayed_sum(2, 2, delay).await); } ```
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;
async fn myasynctest(#[case] a: u32, result: #[case] #[future] u32) {
assert_eq!(2 * a, result.await);
}
``
Just the attributes that ends withtest` (last path segment) can be injected.
#[once] FixtureIf you need to a fixture that should be inizialized 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
fn once_fixture() -> i32 { 42 }
fn single(oncefixture: &i32) { // All tests that use oncefixture will share the same reference to oncefixture() // function result. asserteq!(&42, once_fixture) } ```
All these features can be used together with a mixture of fixture variables, fixed cases and 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::*;
fn repository() -> InMemoryRepository { let mut r = InMemoryRepository::default(); // fill repository with some data r }
fn alice() -> User { User::logged("Alice", "2001-10-04", "London", "UK") }
fixture also as standard functionguest in this case // and `authed_user`
fn shouldbeinvalidqueryerror( repository: impl Repository, #[case] user: User, #[values(" ", "^%$#@!", "....")] query: &str ) { repository.find_items(&user, query).unwrap(); } ```
This example will generate exactly 6 tests grouped by 2 different cases:
``` running 6 tests test shouldbeinvalidqueryerror::case1autheduser::query1 ... ok test shouldbeinvalidqueryerror::case2guest::query2 ... ok test shouldbeinvalidqueryerror::case2guest::query3 ... ok test shouldbeinvalidqueryerror::case1autheduser::query2 ... ok test shouldbeinvalidqueryerror::case1autheduser::query3 ... ok test shouldbeinvalidqueryerror::case2guest::query_1 ... ok
test result: ok. 6 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out ```
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
fn user(#[default("Alice")] name: &str, #[default(22)] age: u8) -> User { User::new(name, age) }
fn isalice(user: User) { asserteq!(user.name(), "Alice") }
fn is22(user: User) { asserteq!(user.age(), 22) }
fn isbob(#[with("Bob")] user: User) { asserteq!(user.name(), "Bob") }
fn is42(#[with("", 42)] user: User) { asserteq!(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
fn should_fail(#[case] number: u32, #[case] name: &str, #[case] tuple: (&str, i32)) { assert!(false); // <- stdout come out just for failed tests } ```
``` running 2 tests test shouldfail::case1 ... FAILED test shouldfail::case2 ... FAILED
failures:
---- shouldfail::case1 stdout ----
------------ TEST ARGUMENTS ------------
number = 42
name = "FortyTwo"
tuple = ("minus twelve", -12)
-------------- TEST START --------------
thread 'shouldfail::case1' panicked at 'assertion failed: false', src/main.rs:64:5
note: run with RUST_BACKTRACE=1 environment variable to display a backtrace.
---- shouldfail::case2 stdout ---- ------------ TEST ARGUMENTS ------------ number = 24 name = "TwentyFour" tuple = ("minus twentyfour", -24) -------------- TEST START -------------- thread 'shouldfail::case2' panicked at 'assertion failed: false', src/main.rs:64:5
failures: shouldfail::case1 shouldfail::case2
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 and find more examples in
tests/resources directory.
See CHANGELOG.md
Licensed under either of
Apache License, Version 2.0, (LICENSE-APACHE or [license-apache-link])
MIT license LICENSE-MIT or [license-MIT-link] at your option.