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 = "0.7.1"
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:
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);
}
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.
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:
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:
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.
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 .
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(a: u32, b: u32) {
assert!(a == b);
}
See rstest_reuse
for more dettails.
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:
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 it's 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.
To use this feature, you need to enable attributes
in the async-std
features list in your Cargo.toml
:
async-std = { version = "1.5", features = ["attributes"] }
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:
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, result: #[case] impl Future<Output=u32>) {
assert_eq!(2 * a, result.await);
}
Just the attributes that ends with test
(last path segment) can be injected.
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.
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::authed_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 `authed_user`
#[should_panic(expected = "Invalid query error")] // We whould test a panic
fn should_be_invalid_query_error(
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 should_be_invalid_query_error::case_1_authed_user::query_1 ... ok
test should_be_invalid_query_error::case_2_guest::query_2 ... ok
test should_be_invalid_query_error::case_2_guest::query_3 ... ok
test should_be_invalid_query_error::case_1_authed_user::query_2 ... ok
test should_be_invalid_query_error::case_1_authed_user::query_3 ... ok
test should_be_invalid_query_error::case_2_guest::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.
#[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.
#[rstest]
#[case(42, "FortyTwo", ("minus twelve", -12))]
#[case(24, "TwentyFour", ("minus twentyfour", -24))]
#[trace] //This attribute enable traceing
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 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 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.