mos-test

mos-test is port of great [defmt-test] to [mos] architecture. It is a alternative test harness that lets you write and run unit tests on all llvm-mos platforms as if you were using the built-in #[test] attribute.

It is compatible with [rust-analyzer]'s ▶ Run Test button, which means you can run your tests straight from VS Code

For a full list of mos-test's capabilities, please refer to the documentation below.

Adding mos-test to an existing project

If you want to add mos-test to an existing Cargo project / package, for each crate that you want to test you need to do these changes in Cargo.toml:

``` toml

Cargo.toml

for the library crate (src/lib.rs)

[lib] harness = false

for the bin crate (src/main.rs)

[[bin]] name = "binary_name" harness = false

for each crate in the tests directory

[[test]] name = "test-name" # tests/test-name.rs harness = false

[[test]] name = "second" # tests/second.rs harness = false ```

The other thing to be aware is that cargo test will compile all crates in the package, or workspace. This may include crates that you don't want to test, like src/main.rs or each crate in src/bin or examples. To identify which crates are being compiled by cargo test, run cargo test -j1 -v and look for the --crate-name flag passed to each rustc invocation.

To test only a subset of the crates in the package / workspace you have two options:

if you have this project structure

console $ tree . . ├── Cargo.toml ├── src │ ├── lib.rs │ └── main.rs └── tests └── integration.rs

and have src/lib.rs set up for tests but don't want to test src/main.rs you'll need to disable tests for src/main.rs

``` toml

Cargo.toml

[package]

..

name = "app"

[[bin]] # <- add this section name = "app" # src/main.rs test = false ```

Adding state

An #[init] function can be written within the #[tests] module. This function will be executed before all unit tests and its return value, the test suite state, can be passed to unit tests as an argument.

``` rust // state shared across unit tests struct MyState { flag: bool, }

[defmt_test::tests]

mod tests { #[init] fn init() -> super::MyState { // state initial value super::MyState { flag: true, } }

// This function is called before each test case.
// It accesses the state created in `init`,
// though like with `test`, state access is optional.
#[before_each]
fn before_each(state: &mut super::MyState) {
    defmt::println!("State flag before is {}", state.flag);
}

// This function is called after each test
#[after_each]
fn after_each(state: &mut super::MyState) {
    defmt::println!("State flag after is {}", state.flag);
}

// this unit test doesn't access the state
#[test]
fn assert_true() {
    assert!(true);
}

// but this test does
#[test]
fn assert_flag(state: &mut super::MyState) {
    assert!(state.flag)
    state.flag = false;
}

} ```

console $ cargo test -p testsuite 0.000000 (1/2) running `assert_true`... └─ integration::tests::__defmt_test_entry @ tests/integration.rs:37 0.000001 State flag before is true └─ integration::tests::before_each @ tests/integration.rs:26 0.000002 State flag after is true └─ integration::tests::after_each @ tests/integration.rs:32 0.000003 (2/2) running `assert_flag`... └─ integration::tests::__defmt_test_entry @ tests/integration.rs:43 0.000004 State flag before is true └─ integration::tests::before_each @ tests/integration.rs:26 0.000005 State flag after is false └─ integration::tests::after_each @ tests/integration.rs:32 0.000006 all tests passed! └─ integration::tests::__defmt_test_entry @ tests/integration.rs:11

Test Outcome

Test functions may either return () and panic on failure, or return any other type that implements the TestOutcome trait, such as Result.

This allows tests to indicate failure via Result, which allows using the ? operator to propagate errors.

Similar to Rust's built-in #[should_panic] attribute, mos-test supports a #[should_error] attribute, which inverts the meaning of the returned TestOutcome. Err makes the test pass, while Ok/() make it fail.

License

Licensed under either of

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be licensed as above, without any additional terms or conditions.