There was no documentation yet on the KUnit-based `#[test]`s.
Thus add it now.
It includes an explanation about the `assert*!` macros being mapped to KUnit and the support for `-> Result` introduced in these series.
Signed-off-by: Miguel Ojeda ojeda@kernel.org --- Documentation/rust/testing.rst | 71 ++++++++++++++++++++++++++++++++++ 1 file changed, 71 insertions(+)
diff --git a/Documentation/rust/testing.rst b/Documentation/rust/testing.rst index 6337b83815ab..f43cb77bcc69 100644 --- a/Documentation/rust/testing.rst +++ b/Documentation/rust/testing.rst @@ -130,6 +130,77 @@ please see:
https://rust.docs.kernel.org/kernel/error/type.Result.html#error-codes-in-c-...
+The ``#[test]`` tests +--------------------- + +Additionally, there are the ``#[test]`` tests. Like for documentation tests, +these are also fairly similar to what you would expect from userspace, and they +are also mapped to KUnit. + +These tests are introduced by the ``kunit_tests`` procedural macro, which takes +the name of the test suite as an argument. + +For instance, assume we want to test the function ``f`` from the documentation +tests section. We could write, in the same file where we have our function: + +.. code-block:: rust + + #[kunit_tests(rust_kernel_mymod)] + mod tests { + use super::*; + + #[test] + fn test_f() { + assert_eq!(f(10, 20), 30); + } + } + +And if we run it, the kernel log would look like:: + + KTAP version 1 + # Subtest: rust_kernel_mymod + # speed: normal + 1..1 + # test_f.speed: normal + ok 1 test_f + ok 1 rust_kernel_mymod + +Like documentation tests, the ``assert!`` and ``assert_eq!`` macros are mapped +back to KUnit and do not panic. Similarly, the +`? https://doc.rust-lang.org/reference/expressions/operator-expr.html#the-question-mark-operator`_ +operator is supported, i.e. the test functions may return either nothing (i.e. +the unit type ``()``) or ``Result`` (i.e. any ``Result<T, E>``). For instance: + +.. code-block:: rust + + #[kunit_tests(rust_kernel_mymod)] + mod tests { + use super::*; + + #[test] + fn test_g() -> Result { + let x = g()?; + assert_eq!(x, 30); + Ok(()) + } + } + +If we run the test and the call to ``g`` fails, then the kernel log would show:: + + KTAP version 1 + # Subtest: rust_kernel_mymod + # speed: normal + 1..1 + # test_g: ASSERTION FAILED at rust/kernel/lib.rs:335 + Expected is_test_result_ok(test_g()) to be true, but is false + # test_g.speed: normal + not ok 1 test_g + not ok 1 rust_kernel_mymod + +If a ``#[test]`` test could be useful as an example for the user, then please +use a documentation test instead. Even edge cases of an API, e.g. error or +boundary cases, can be interesting to show in examples. + The ``rusttest`` host tests ---------------------------