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Diffstat (limited to 'Documentation/rust/testing.rst')
| -rw-r--r-- | Documentation/rust/testing.rst | 115 |
1 files changed, 108 insertions, 7 deletions
diff --git a/Documentation/rust/testing.rst b/Documentation/rust/testing.rst index 6658998d1b6c..f43cb77bcc69 100644 --- a/Documentation/rust/testing.rst +++ b/Documentation/rust/testing.rst @@ -6,10 +6,11 @@ Testing This document contains useful information how to test the Rust code in the kernel. -There are two sorts of tests: +There are three sorts of tests: - The KUnit tests. - The ``#[test]`` tests. +- The Kselftests. The KUnit tests --------------- @@ -96,7 +97,7 @@ operator are also supported as usual, e.g.: /// ``` /// # use kernel::{spawn_work_item, workqueue}; - /// spawn_work_item!(workqueue::system(), || pr_info!("x"))?; + /// spawn_work_item!(workqueue::system(), || pr_info!("x\n"))?; /// # Ok::<(), Error>(()) /// ``` @@ -122,14 +123,114 @@ A current limitation is that KUnit does not support assertions in other tasks. Thus, we presently simply print an error to the kernel log if an assertion actually failed. Additionally, doctests are not run for nonpublic functions. +Since these tests are examples, i.e. they are part of the documentation, they +should generally be written like "real code". Thus, for example, instead of +using ``unwrap()`` or ``expect()``, use the ``?`` operator. For more background, +please see: + + https://rust.docs.kernel.org/kernel/error/type.Result.html#error-codes-in-c-and-rust + The ``#[test]`` tests --------------------- -Additionally, there are the ``#[test]`` tests. These can be run using the -``rusttest`` Make target:: +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 +--------------------------- + +These are userspace tests that can be built and run in the host (i.e. the one +that performs the kernel build) using the ``rusttest`` Make target:: make LLVM=1 rusttest -This requires the kernel ``.config`` and downloads external repositories. It -runs the ``#[test]`` tests on the host (currently) and thus is fairly limited in -what these tests can test. +This requires the kernel ``.config``. + +Currently, they are mostly used for testing the ``macros`` crate's examples. + +The Kselftests +-------------- + +Kselftests are also available in the ``tools/testing/selftests/rust`` folder. + +The kernel config options required for the tests are listed in the +``tools/testing/selftests/rust/config`` file and can be included with the aid +of the ``merge_config.sh`` script:: + + ./scripts/kconfig/merge_config.sh .config tools/testing/selftests/rust/config + +The kselftests are built within the kernel source tree and are intended to +be executed on a system that is running the same kernel. + +Once a kernel matching the source tree has been installed and booted, the +tests can be compiled and executed using the following command:: + + make TARGETS="rust" kselftest + +Refer to Documentation/dev-tools/kselftest.rst for the general Kselftest +documentation. |