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 = "0.19.0"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:
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 outIf 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(#[case] a: u32, #[case] b: u32) {
assert!(a == b);
}See rstest_reuse for more details.
In case you want certain test cases to only be present if a certain feature is
enabled, use #[cfg_attr(feature = …, case(…))]:
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.
If you need a value where its type implement FromStr() trait you can use a literal
string to build it:
# 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.
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 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.
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 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:
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:
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);
}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.
#[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 set a default timeout for test using the RSTEST_TIMEOUT environment variable.
The value is in seconds and is evaluated on test compile time.
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:
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.
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).
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, #[case] #[future] result: u32) {
assert_eq!(2 * a, result.await);
}Just the attributes that ends with test (last path segment) can be injected.
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:
#[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)
}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.
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:
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.
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 tracing
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.
The minimum supported Rust version is 1.67.1.
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.
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