[PATCH v2 0/3] rust: kunit: Support KUnit tests with a user-space like syntax

[PATCH v2 0/3] rust: kunit: Support KUnit tests with a user-space like syntax

[David Gow]

This series was originally written by José Expósito, and has been
modified and updated by Matt Gilbride and myself. The original version
can be found here:
https://github.com/Rust-for-Linux/linux/pull/950

Add support for writing KUnit tests in Rust. While Rust doctests are
already converted to KUnit tests and run, they're really better suited
for examples, rather than as first-class unit tests.

This series implements a series of direct Rust bindings for KUnit tests,
as well as a new macro which allows KUnit tests to be written using a
close variant of normal Rust unit test syntax. The only change required
is replacing '#[cfg(test)]' with '#[kunit_tests(kunit_test_suite_name)]'

An example test would look like:
	#[kunit_tests(rust_kernel_hid_driver)]
	mod tests {
	    use super::*;
	    use crate::{c_str, driver, hid, prelude::*};
	    use core::ptr;

	    struct SimpleTestDriver;
	    impl Driver for SimpleTestDriver {
	        type Data = ();
	    }

	    #[test]
	    fn rust_test_hid_driver_adapter() {
	        let mut hid = bindings::hid_driver::default();
	        let name = c_str!("SimpleTestDriver");
	        static MODULE: ThisModule = unsafe { ThisModule::from_ptr(ptr::null_mut()) };

        	let res = unsafe {
	            <hid::Adapter<SimpleTestDriver> as driver::DriverOps>::register(&mut hid, name, &MODULE)
	        };
	        assert_eq!(res, Err(ENODEV)); // The mock returns -19
	    }
	}


Please give this a go, and make sure I haven't broken it! There's almost
certainly a lot of improvements which can be made -- and there's a fair
case to be made for replacing some of this with generated C code which
can use the C macros -- but this is hopefully an adequate implementation
for now, and the interface can (with luck) remain the same even if the
implementation changes.

A few small notable missing features:
- Attributes (like the speed of a test) are hardcoded to the default
  value.
- Similarly, the module name attribute is hardcoded to NULL. In C, we
  use the KBUILD_MODNAME macro, but I couldn't find a way to use this
  from Rust which wasn't more ugly than just disabling it.
- Assertions are not automatically rewritten to use KUnit assertions.

---

Changes since v1:
https://lore.kernel.org/lkml/20230720-rustbind-v1-0-c80db349e3b5@google.com/T/
- Rebase on top of the latest rust-next (commit 718c4069896c)
- Make kunit_case a const fn, rather than a macro (Thanks Boqun)
- As a result, the null terminator is now created with
  kernel::kunit::kunit_case_null()
- Use the C kunit_get_current_test() function to implement
  in_kunit_test(), rather than re-implementing it (less efficiently)
  ourselves.

Changes since the GitHub PR:
- Rebased on top of kselftest/kunit
- Add const_mut_refs feature
  This may conflict with https://lore.kernel.org/lkml/20230503090708.2524310-6-nmi@metaspace.dk/
- Add rust/macros/kunit.rs to the KUnit MAINTAINERS entry

---
José Expósito (3):
  rust: kunit: add KUnit case and suite macros
  rust: macros: add macro to easily run KUnit tests
  rust: kunit: allow to know if we are in a test

 MAINTAINERS          |   1 +
 rust/kernel/kunit.rs | 191 +++++++++++++++++++++++++++++++++++++++++++
 rust/kernel/lib.rs   |   1 +
 rust/macros/lib.rs   |  29 +++++++
 4 files changed, 222 insertions(+)

-- 
2.47.0.163.g1226f6d8fa-goog

[PATCH v2 1/3] rust: kunit: add KUnit case and suite macros

[David Gow]

From: José Expósito <jose.exposito89@gmail.com>

Add a couple of Rust const functions and macros to allow to develop
KUnit tests without relying on generated C code:

 - The `kunit_unsafe_test_suite!` Rust macro is similar to the
   `kunit_test_suite` C macro. It requires a NULL-terminated array of
   test cases (see below).
 - The `kunit_case` Rust function is similar to the `KUNIT_CASE` C macro.
   It generates as case from the name and function.
 - The `kunit_case_null` Rust function generates a NULL test case, which
   is to be used as delimiter in `kunit_test_suite!`.

While these functions and macros can be used on their own, a future
patch will introduce another macro to create KUnit tests using a
user-space like syntax.

Signed-off-by: José Expósito <jose.exposito89@gmail.com>
Co-developed-by: Matt Gilbride <mattgilbride@google.com>
Signed-off-by: Matt Gilbride <mattgilbride@google.com>
Co-developed-by: David Gow <davidgow@google.com>
Signed-off-by: David Gow <davidgow@google.com>
---

Changes since v1:
https://lore.kernel.org/lkml/20230720-rustbind-v1-1-c80db349e3b5@google.com/
- Rebase on top of rust-next
- As a result, KUnit attributes are new set. These are hardcoded to the
  defaults of "normal" speed and no module name.
- Split the kunit_case!() macro into two const functions, kunit_case()
  and kunit_case_null() (for the NULL terminator).

---
 rust/kernel/kunit.rs | 108 +++++++++++++++++++++++++++++++++++++++++++
 rust/kernel/lib.rs   |   1 +
 2 files changed, 109 insertions(+)

diff --git a/rust/kernel/kunit.rs b/rust/kernel/kunit.rs
index 824da0e9738a..fc2d259db458 100644
--- a/rust/kernel/kunit.rs
+++ b/rust/kernel/kunit.rs
@@ -161,3 +161,111 @@ macro_rules! kunit_assert_eq {
         $crate::kunit_assert!($name, $file, $diff, $left == $right);
     }};
 }
+
+/// Represents an individual test case.
+///
+/// The test case should have the signature
+/// `unsafe extern "C" fn test_case(test: *mut crate::bindings::kunit)`.
+///
+/// The `kunit_unsafe_test_suite!` macro expects a NULL-terminated list of test cases.
+/// Use `kunit_case_null` to generate such a delimeter.
+const fn kunit_case(name: &kernel::str::CStr, run_case: unsafe extern "C" fn(*mut kernel::bindings::kunit)) -> kernel::bindings::kunit_case {
+    kernel::bindings::kunit_case {
+        run_case: Some(run_case),
+        name: name.as_char_ptr(),
+        attr: kernel::bindings::kunit_attributes {
+            speed: kernel::bindings::kunit_speed_KUNIT_SPEED_NORMAL,
+        },
+        generate_params: None,
+        status: kernel::bindings::kunit_status_KUNIT_SUCCESS,
+        module_name: core::ptr::null_mut(),
+        log: core::ptr::null_mut(),
+    }
+}
+
+/// Represents the NULL test case delimiter.
+///
+/// The `kunit_unsafe_test_suite!` macro expects a NULL-terminated list of test cases. This
+/// function retuns such a delimiter.
+const fn kunit_case_null() -> kernel::bindings::kunit_case {
+    kernel::bindings::kunit_case {
+        run_case: None,
+        name: core::ptr::null_mut(),
+        generate_params: None,
+        attr: kernel::bindings::kunit_attributes {
+            speed: kernel::bindings::kunit_speed_KUNIT_SPEED_NORMAL,
+        },
+        status: kernel::bindings::kunit_status_KUNIT_SUCCESS,
+        module_name: core::ptr::null_mut(),
+        log: core::ptr::null_mut(),
+    }
+}
+
+
+/// Registers a KUnit test suite.
+///
+/// # Safety
+///
+/// `test_cases` must be a NULL terminated array of test cases.
+///
+/// # Examples
+///
+/// ```ignore
+/// unsafe extern "C" fn test_fn(_test: *mut crate::bindings::kunit) {
+///     let actual = 1 + 1;
+///     let expected = 2;
+///     assert_eq!(actual, expected);
+/// }
+///
+/// static mut KUNIT_TEST_CASE: crate::bindings::kunit_case = crate::kunit_case(name, test_fn);
+/// static mut KUNIT_NULL_CASE: crate::bindings::kunit_case = crate::kunit_case_null();
+/// static mut KUNIT_TEST_CASES: &mut[crate::bindings::kunit_case] = unsafe {
+///     &mut[KUNIT_TEST_CASE, KUNIT_NULL_CASE]
+/// };
+/// crate::kunit_unsafe_test_suite!(suite_name, KUNIT_TEST_CASES);
+/// ```
+#[macro_export]
+macro_rules! kunit_unsafe_test_suite {
+    ($name:ident, $test_cases:ident) => {
+        const _: () = {
+            static KUNIT_TEST_SUITE_NAME: [i8; 256] = {
+                let name_u8 = core::stringify!($name).as_bytes();
+                let mut ret = [0; 256];
+
+                let mut i = 0;
+                while i < name_u8.len() {
+                    ret[i] = name_u8[i] as i8;
+                    i += 1;
+                }
+
+                ret
+            };
+
+            static mut KUNIT_TEST_SUITE: core::cell::UnsafeCell<$crate::bindings::kunit_suite> =
+                core::cell::UnsafeCell::new($crate::bindings::kunit_suite {
+                    name: KUNIT_TEST_SUITE_NAME,
+                    // SAFETY: User is expected to pass a correct `test_cases`, hence this macro
+                    // named 'unsafe'.
+                    test_cases: unsafe { $test_cases.as_mut_ptr() },
+                    suite_init: None,
+                    suite_exit: None,
+                    init: None,
+                    exit: None,
+                    attr: $crate::bindings::kunit_attributes {
+                        speed: $crate::bindings::kunit_speed_KUNIT_SPEED_NORMAL,
+                    },
+                    status_comment: [0; 256usize],
+                    debugfs: core::ptr::null_mut(),
+                    log: core::ptr::null_mut(),
+                    suite_init_err: 0,
+                    is_init: false,
+                });
+
+            #[used]
+            #[link_section = ".kunit_test_suites"]
+            static mut KUNIT_TEST_SUITE_ENTRY: *const $crate::bindings::kunit_suite =
+                // SAFETY: `KUNIT_TEST_SUITE` is static.
+                unsafe { KUNIT_TEST_SUITE.get() };
+        };
+    };
+}
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index b62451f64f6e..d662aa37070f 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -18,6 +18,7 @@
 #![feature(inline_const)]
 #![feature(lint_reasons)]
 #![feature(unsize)]
+#![feature(const_mut_refs)]
 
 // Ensure conditional compilation based on the kernel configuration works;
 // otherwise we may silently break things like initcall handling.
-- 
2.47.0.163.g1226f6d8fa-goog

[PATCH v2 2/3] rust: macros: add macro to easily run KUnit tests

[David Gow]

From: José Expósito <jose.exposito89@gmail.com>

Add a new procedural macro (`#[kunit_tests(kunit_test_suit_name)]`) to
run KUnit tests using a user-space like syntax.

The macro, that should be used on modules, transforms every `#[test]`
in a `kunit_case!` and adds a `kunit_unsafe_test_suite!` registering
all of them.

The only difference with user-space tests is that instead of using
`#[cfg(test)]`, `#[kunit_tests(kunit_test_suit_name)]` is used.

Note that `#[cfg(CONFIG_KUNIT)]` is added so the test module is not
compiled when `CONFIG_KUNIT` is set to `n`.

Reviewed-by: David Gow <davidgow@google.com>
Signed-off-by: José Expósito <jose.exposito89@gmail.com>
[Updated to use new const fn.]
Signed-off-by: David Gow <davidgow@google.com>
---

Changes since v1:
https://lore.kernel.org/lkml/20230720-rustbind-v1-2-c80db349e3b5@google.com/
- Rebased on top of rust-next
- Make use of the new const functions, rather than the kunit_case!()
  macro.

---
 MAINTAINERS          |  1 +
 rust/kernel/kunit.rs | 11 +++++++++++
 rust/macros/lib.rs   | 29 +++++++++++++++++++++++++++++
 3 files changed, 41 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index b77f4495dcf4..b65035ede675 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -12433,6 +12433,7 @@ F:	Documentation/dev-tools/kunit/
 F:	include/kunit/
 F:	lib/kunit/
 F:	rust/kernel/kunit.rs
+F:	rust/macros/kunit.rs
 F:	scripts/rustdoc_test_*
 F:	tools/testing/kunit/
 
diff --git a/rust/kernel/kunit.rs b/rust/kernel/kunit.rs
index fc2d259db458..abcf0229ffee 100644
--- a/rust/kernel/kunit.rs
+++ b/rust/kernel/kunit.rs
@@ -40,6 +40,8 @@ pub fn info(args: fmt::Arguments<'_>) {
     }
 }
 
+use macros::kunit_tests;
+
 /// Asserts that a boolean expression is `true` at runtime.
 ///
 /// Public but hidden since it should only be used from generated tests.
@@ -269,3 +271,12 @@ macro_rules! kunit_unsafe_test_suite {
         };
     };
 }
+
+#[kunit_tests(rust_kernel_kunit)]
+mod tests {
+    #[test]
+    fn rust_test_kunit_kunit_tests() {
+        let running = true;
+        assert_eq!(running, true);
+    }
+}
diff --git a/rust/macros/lib.rs b/rust/macros/lib.rs
index 939ae00b723a..098925b99982 100644
--- a/rust/macros/lib.rs
+++ b/rust/macros/lib.rs
@@ -10,6 +10,7 @@
 mod quote;
 mod concat_idents;
 mod helpers;
+mod kunit;
 mod module;
 mod paste;
 mod pin_data;
@@ -430,3 +431,31 @@ pub fn paste(input: TokenStream) -> TokenStream {
 pub fn derive_zeroable(input: TokenStream) -> TokenStream {
     zeroable::derive(input)
 }
+
+/// Registers a KUnit test suite and its test cases using a user-space like syntax.
+///
+/// This macro should be used on modules. If `CONFIG_KUNIT` (in `.config`) is `n`, the target module
+/// is ignored.
+///
+/// # Examples
+///
+/// ```ignore
+/// # use macros::kunit_tests;
+///
+/// #[kunit_tests(kunit_test_suit_name)]
+/// mod tests {
+///     #[test]
+///     fn foo() {
+///         assert_eq!(1, 1);
+///     }
+///
+///     #[test]
+///     fn bar() {
+///         assert_eq!(2, 2);
+///     }
+/// }
+/// ```
+#[proc_macro_attribute]
+pub fn kunit_tests(attr: TokenStream, ts: TokenStream) -> TokenStream {
+    kunit::kunit_tests(attr, ts)
+}
-- 
2.47.0.163.g1226f6d8fa-goog

[PATCH v2 3/3] rust: kunit: allow to know if we are in a test

[David Gow]

From: José Expósito <jose.exposito89@gmail.com>

In some cases, we need to call test-only code from outside the test
case, for example, to mock a function or a module.

In order to check whether we are in a test or not, we need to test if
`CONFIG_KUNIT` is set.
Unfortunately, we cannot rely only on this condition because:
- a test could be running in another thread,
- some distros compile KUnit in production kernels, so checking at runtime
  that `current->kunit_test != NULL` is required.

Forturately, KUnit provides an optimised check in
`kunit_get_current_test()`, which checks CONFIG_KUNIT, a global static
key, and then the current thread's running KUnit test.

Add a safe wrapper function around this to know whether or not we are in
a KUnit test and examples showing how to mock a function and a module.

Signed-off-by: José Expósito <jose.exposito89@gmail.com>
Co-developed-by: David Gow <davidgow@google.com>
Signed-off-by: David Gow <davidgow@google.com>
---

Changes since v1:
https://lore.kernel.org/lkml/20230720-rustbind-v1-3-c80db349e3b5@google.com/
- Rebased on top of rust-next.
- Use the `kunit_get_current_test()` C function, which wasn't previously
  available, instead of rolling our own.
- (Thanks also to Boqun for suggesting a nicer way of implementing this,
  which I tried, but the `kunit_get_current_test()` version obsoleted.)

---
 rust/kernel/kunit.rs | 72 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 72 insertions(+)

diff --git a/rust/kernel/kunit.rs b/rust/kernel/kunit.rs
index abcf0229ffee..bfc80394546a 100644
--- a/rust/kernel/kunit.rs
+++ b/rust/kernel/kunit.rs
@@ -272,11 +272,83 @@ macro_rules! kunit_unsafe_test_suite {
     };
 }
 
+/// In some cases, you need to call test-only code from outside the test case, for example, to
+/// create a function mock. This function can be invoked to know whether we are currently running a
+/// KUnit test or not.
+///
+/// # Examples
+///
+/// This example shows how a function can be mocked to return a well-known value while testing:
+///
+/// ```
+/// # use kernel::kunit::in_kunit_test;
+/// #
+/// fn fn_mock_example(n: i32) -> i32 {
+///     if in_kunit_test() {
+///         100
+///     } else {
+///         n + 1
+///     }
+/// }
+///
+/// let mock_res = fn_mock_example(5);
+/// assert_eq!(mock_res, 100);
+/// ```
+///
+/// Sometimes, you don't control the code that needs to be mocked. This example shows how the
+/// `bindings` module can be mocked:
+///
+/// ```
+/// // Import our mock naming it as the real module.
+/// #[cfg(CONFIG_KUNIT)]
+/// use bindings_mock_example as bindings;
+///
+/// // This module mocks `bindings`.
+/// mod bindings_mock_example {
+///     use kernel::kunit::in_kunit_test;
+///     use kernel::bindings::u64_;
+///
+///     // Make the other binding functions available.
+///     pub(crate) use kernel::bindings::*;
+///
+///     // Mock `ktime_get_boot_fast_ns` to return a well-known value when running a KUnit test.
+///     pub(crate) unsafe fn ktime_get_boot_fast_ns() -> u64_ {
+///         if in_kunit_test() {
+///             1234
+///         } else {
+///             unsafe { kernel::bindings::ktime_get_boot_fast_ns() }
+///         }
+///     }
+/// }
+///
+/// // This is the function we want to test. Since `bindings` has been mocked, we can use its
+/// // functions seamlessly.
+/// fn get_boot_ns() -> u64 {
+///     unsafe { bindings::ktime_get_boot_fast_ns() }
+/// }
+///
+/// let time = get_boot_ns();
+/// assert_eq!(time, 1234);
+/// ```
+pub fn in_kunit_test() -> bool {
+    // SAFETY: kunit_get_current_test() is always safe to call from C (it has fallbacks for
+    // when KUnit is not enabled), and we're only comparing the result to NULL.
+    unsafe { !bindings::kunit_get_current_test().is_null() }
+}
+
 #[kunit_tests(rust_kernel_kunit)]
 mod tests {
+    use super::*;
+
     #[test]
     fn rust_test_kunit_kunit_tests() {
         let running = true;
         assert_eq!(running, true);
     }
+
+    #[test]
+    fn rust_test_kunit_in_kunit_test() {
+        let in_kunit = in_kunit_test();
+        assert_eq!(in_kunit, true);
+    }
 }
-- 
2.47.0.163.g1226f6d8fa-goog

Re: [PATCH v2 1/3] rust: kunit: add KUnit case and suite macros

[Alice Ryhl]

On Tue, Oct 29, 2024 at 10:24 AM David Gow <davidgow@google.com> wrote:
>
> From: José Expósito <jose.exposito89@gmail.com>
>
> Add a couple of Rust const functions and macros to allow to develop
> KUnit tests without relying on generated C code:
>
>  - The `kunit_unsafe_test_suite!` Rust macro is similar to the
>    `kunit_test_suite` C macro. It requires a NULL-terminated array of
>    test cases (see below).
>  - The `kunit_case` Rust function is similar to the `KUNIT_CASE` C macro.
>    It generates as case from the name and function.
>  - The `kunit_case_null` Rust function generates a NULL test case, which
>    is to be used as delimiter in `kunit_test_suite!`.
>
> While these functions and macros can be used on their own, a future
> patch will introduce another macro to create KUnit tests using a
> user-space like syntax.
>
> Signed-off-by: José Expósito <jose.exposito89@gmail.com>
> Co-developed-by: Matt Gilbride <mattgilbride@google.com>
> Signed-off-by: Matt Gilbride <mattgilbride@google.com>
> Co-developed-by: David Gow <davidgow@google.com>
> Signed-off-by: David Gow <davidgow@google.com>
> ---
>
> Changes since v1:
> https://lore.kernel.org/lkml/20230720-rustbind-v1-1-c80db349e3b5@google.com/
> - Rebase on top of rust-next
> - As a result, KUnit attributes are new set. These are hardcoded to the
>   defaults of "normal" speed and no module name.
> - Split the kunit_case!() macro into two const functions, kunit_case()
>   and kunit_case_null() (for the NULL terminator).
>
> ---
>  rust/kernel/kunit.rs | 108 +++++++++++++++++++++++++++++++++++++++++++
>  rust/kernel/lib.rs   |   1 +
>  2 files changed, 109 insertions(+)
>
> diff --git a/rust/kernel/kunit.rs b/rust/kernel/kunit.rs
> index 824da0e9738a..fc2d259db458 100644
> --- a/rust/kernel/kunit.rs
> +++ b/rust/kernel/kunit.rs
> @@ -161,3 +161,111 @@ macro_rules! kunit_assert_eq {
>          $crate::kunit_assert!($name, $file, $diff, $left == $right);
>      }};
>  }
> +
> +/// Represents an individual test case.
> +///
> +/// The test case should have the signature
> +/// `unsafe extern "C" fn test_case(test: *mut crate::bindings::kunit)`.
> +///
> +/// The `kunit_unsafe_test_suite!` macro expects a NULL-terminated list of test cases.
> +/// Use `kunit_case_null` to generate such a delimeter.
> +const fn kunit_case(name: &kernel::str::CStr, run_case: unsafe extern "C" fn(*mut kernel::bindings::kunit)) -> kernel::bindings::kunit_case {

This should probably say `name: &'static CStr` to require that the
name lives forever.

> +/// Registers a KUnit test suite.
> +///
> +/// # Safety
> +///
> +/// `test_cases` must be a NULL terminated array of test cases.
> +///
> +/// # Examples
> +///
> +/// ```ignore
> +/// unsafe extern "C" fn test_fn(_test: *mut crate::bindings::kunit) {
> +///     let actual = 1 + 1;
> +///     let expected = 2;
> +///     assert_eq!(actual, expected);
> +/// }
> +///
> +/// static mut KUNIT_TEST_CASE: crate::bindings::kunit_case = crate::kunit_case(name, test_fn);
> +/// static mut KUNIT_NULL_CASE: crate::bindings::kunit_case = crate::kunit_case_null();
> +/// static mut KUNIT_TEST_CASES: &mut[crate::bindings::kunit_case] = unsafe {
> +///     &mut[KUNIT_TEST_CASE, KUNIT_NULL_CASE]
> +/// };
> +/// crate::kunit_unsafe_test_suite!(suite_name, KUNIT_TEST_CASES);
> +/// ```
> +#[macro_export]
> +macro_rules! kunit_unsafe_test_suite {
> +    ($name:ident, $test_cases:ident) => {
> +        const _: () = {
> +            static KUNIT_TEST_SUITE_NAME: [i8; 256] = {
> +                let name_u8 = core::stringify!($name).as_bytes();
> +                let mut ret = [0; 256];
> +
> +                let mut i = 0;
> +                while i < name_u8.len() {
> +                    ret[i] = name_u8[i] as i8;
> +                    i += 1;
> +                }

I assume the name must be zero-terminated? If so, you probably need to
enforce that somehow, e.g. by failing if `name_u8` is longer than 255
bytes.

> +
> +            static mut KUNIT_TEST_SUITE: core::cell::UnsafeCell<$crate::bindings::kunit_suite> =

You don't actually need UnsafeCell here since it's already `static mut`.

> +                core::cell::UnsafeCell::new($crate::bindings::kunit_suite {
> +                    name: KUNIT_TEST_SUITE_NAME,
> +                    // SAFETY: User is expected to pass a correct `test_cases`, hence this macro
> +                    // named 'unsafe'.
> +                    test_cases: unsafe { $test_cases.as_mut_ptr() },
> +                    suite_init: None,
> +                    suite_exit: None,
> +                    init: None,
> +                    exit: None,
> +                    attr: $crate::bindings::kunit_attributes {
> +                        speed: $crate::bindings::kunit_speed_KUNIT_SPEED_NORMAL,
> +                    },
> +                    status_comment: [0; 256usize],
> +                    debugfs: core::ptr::null_mut(),
> +                    log: core::ptr::null_mut(),
> +                    suite_init_err: 0,
> +                    is_init: false,
> +                });
> +
> +            #[used]
> +            #[link_section = ".kunit_test_suites"]
> +            static mut KUNIT_TEST_SUITE_ENTRY: *const $crate::bindings::kunit_suite =
> +                // SAFETY: `KUNIT_TEST_SUITE` is static.
> +                unsafe { KUNIT_TEST_SUITE.get() };

If you change `KUNIT_TEST_SUITE` to not be an UnsafeCell, then you'll
want to do `core::ptr::addr_of_mut!(KUNIT_TEST_SUITE` instead.

> diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
> index b62451f64f6e..d662aa37070f 100644
> --- a/rust/kernel/lib.rs
> +++ b/rust/kernel/lib.rs
> @@ -18,6 +18,7 @@
>  #![feature(inline_const)]
>  #![feature(lint_reasons)]
>  #![feature(unsize)]
> +#![feature(const_mut_refs)]

Is this still needed with the above changes?

Alice

Re: [PATCH v2 2/3] rust: macros: add macro to easily run KUnit tests

[Boqun Feng]

Hi David,

On Tue, Oct 29, 2024 at 05:24:18PM +0800, David Gow wrote:
> From: José Expósito <jose.exposito89@gmail.com>
> 
> Add a new procedural macro (`#[kunit_tests(kunit_test_suit_name)]`) to
> run KUnit tests using a user-space like syntax.
> 
> The macro, that should be used on modules, transforms every `#[test]`
> in a `kunit_case!` and adds a `kunit_unsafe_test_suite!` registering
> all of them.
> 
> The only difference with user-space tests is that instead of using
> `#[cfg(test)]`, `#[kunit_tests(kunit_test_suit_name)]` is used.
> 
> Note that `#[cfg(CONFIG_KUNIT)]` is added so the test module is not
> compiled when `CONFIG_KUNIT` is set to `n`.
> 
> Reviewed-by: David Gow <davidgow@google.com>
> Signed-off-by: José Expósito <jose.exposito89@gmail.com>
> [Updated to use new const fn.]
> Signed-off-by: David Gow <davidgow@google.com>
> ---
> 
> Changes since v1:
> https://lore.kernel.org/lkml/20230720-rustbind-v1-2-c80db349e3b5@google.com/
> - Rebased on top of rust-next
> - Make use of the new const functions, rather than the kunit_case!()
>   macro.
> 
> ---
>  MAINTAINERS          |  1 +
>  rust/kernel/kunit.rs | 11 +++++++++++
>  rust/macros/lib.rs   | 29 +++++++++++++++++++++++++++++
>  3 files changed, 41 insertions(+)
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index b77f4495dcf4..b65035ede675 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -12433,6 +12433,7 @@ F:	Documentation/dev-tools/kunit/
>  F:	include/kunit/
>  F:	lib/kunit/
>  F:	rust/kernel/kunit.rs
> +F:	rust/macros/kunit.rs

I cannot find this file in this series, and it's not in the current
rust-next either.

(Did you do the same thing as I sometimes did: forget to `git add` a new
file?)

Regards,
Boqun

>  F:	scripts/rustdoc_test_*
>  F:	tools/testing/kunit/
>  
> diff --git a/rust/kernel/kunit.rs b/rust/kernel/kunit.rs
> index fc2d259db458..abcf0229ffee 100644
> --- a/rust/kernel/kunit.rs
> +++ b/rust/kernel/kunit.rs
> @@ -40,6 +40,8 @@ pub fn info(args: fmt::Arguments<'_>) {
>      }
>  }
>  
> +use macros::kunit_tests;
> +
>  /// Asserts that a boolean expression is `true` at runtime.
>  ///
>  /// Public but hidden since it should only be used from generated tests.
> @@ -269,3 +271,12 @@ macro_rules! kunit_unsafe_test_suite {
>          };
>      };
>  }
> +
> +#[kunit_tests(rust_kernel_kunit)]
> +mod tests {
> +    #[test]
> +    fn rust_test_kunit_kunit_tests() {
> +        let running = true;
> +        assert_eq!(running, true);
> +    }
> +}
> diff --git a/rust/macros/lib.rs b/rust/macros/lib.rs
> index 939ae00b723a..098925b99982 100644
> --- a/rust/macros/lib.rs
> +++ b/rust/macros/lib.rs
> @@ -10,6 +10,7 @@
>  mod quote;
>  mod concat_idents;
>  mod helpers;
> +mod kunit;
>  mod module;
>  mod paste;
>  mod pin_data;
> @@ -430,3 +431,31 @@ pub fn paste(input: TokenStream) -> TokenStream {
>  pub fn derive_zeroable(input: TokenStream) -> TokenStream {
>      zeroable::derive(input)
>  }
> +
> +/// Registers a KUnit test suite and its test cases using a user-space like syntax.
> +///
> +/// This macro should be used on modules. If `CONFIG_KUNIT` (in `.config`) is `n`, the target module
> +/// is ignored.
> +///
> +/// # Examples
> +///
> +/// ```ignore
> +/// # use macros::kunit_tests;
> +///
> +/// #[kunit_tests(kunit_test_suit_name)]
> +/// mod tests {
> +///     #[test]
> +///     fn foo() {
> +///         assert_eq!(1, 1);
> +///     }
> +///
> +///     #[test]
> +///     fn bar() {
> +///         assert_eq!(2, 2);
> +///     }
> +/// }
> +/// ```
> +#[proc_macro_attribute]
> +pub fn kunit_tests(attr: TokenStream, ts: TokenStream) -> TokenStream {
> +    kunit::kunit_tests(attr, ts)
> +}
> -- 
> 2.47.0.163.g1226f6d8fa-goog
> 
> 

Re: [PATCH v2 1/3] rust: kunit: add KUnit case and suite macros

[David Gow]

[-- Attachment #1: Type: text/plain, Size: 6678 bytes --]

On Tue, 29 Oct 2024 at 20:08, Alice Ryhl <aliceryhl@google.com> wrote:
>
> On Tue, Oct 29, 2024 at 10:24 AM David Gow <davidgow@google.com> wrote:
> >
> > From: José Expósito <jose.exposito89@gmail.com>
> >
> > Add a couple of Rust const functions and macros to allow to develop
> > KUnit tests without relying on generated C code:
> >
> >  - The `kunit_unsafe_test_suite!` Rust macro is similar to the
> >    `kunit_test_suite` C macro. It requires a NULL-terminated array of
> >    test cases (see below).
> >  - The `kunit_case` Rust function is similar to the `KUNIT_CASE` C macro.
> >    It generates as case from the name and function.
> >  - The `kunit_case_null` Rust function generates a NULL test case, which
> >    is to be used as delimiter in `kunit_test_suite!`.
> >
> > While these functions and macros can be used on their own, a future
> > patch will introduce another macro to create KUnit tests using a
> > user-space like syntax.
> >
> > Signed-off-by: José Expósito <jose.exposito89@gmail.com>
> > Co-developed-by: Matt Gilbride <mattgilbride@google.com>
> > Signed-off-by: Matt Gilbride <mattgilbride@google.com>
> > Co-developed-by: David Gow <davidgow@google.com>
> > Signed-off-by: David Gow <davidgow@google.com>
> > ---
> >
> > Changes since v1:
> > https://lore.kernel.org/lkml/20230720-rustbind-v1-1-c80db349e3b5@google.com/
> > - Rebase on top of rust-next
> > - As a result, KUnit attributes are new set. These are hardcoded to the
> >   defaults of "normal" speed and no module name.
> > - Split the kunit_case!() macro into two const functions, kunit_case()
> >   and kunit_case_null() (for the NULL terminator).
> >
> > ---
> >  rust/kernel/kunit.rs | 108 +++++++++++++++++++++++++++++++++++++++++++
> >  rust/kernel/lib.rs   |   1 +
> >  2 files changed, 109 insertions(+)
> >
> > diff --git a/rust/kernel/kunit.rs b/rust/kernel/kunit.rs
> > index 824da0e9738a..fc2d259db458 100644
> > --- a/rust/kernel/kunit.rs
> > +++ b/rust/kernel/kunit.rs
> > @@ -161,3 +161,111 @@ macro_rules! kunit_assert_eq {
> >          $crate::kunit_assert!($name, $file, $diff, $left == $right);
> >      }};
> >  }
> > +
> > +/// Represents an individual test case.
> > +///
> > +/// The test case should have the signature
> > +/// `unsafe extern "C" fn test_case(test: *mut crate::bindings::kunit)`.
> > +///
> > +/// The `kunit_unsafe_test_suite!` macro expects a NULL-terminated list of test cases.
> > +/// Use `kunit_case_null` to generate such a delimeter.
> > +const fn kunit_case(name: &kernel::str::CStr, run_case: unsafe extern "C" fn(*mut kernel::bindings::kunit)) -> kernel::bindings::kunit_case {
>
> This should probably say `name: &'static CStr` to require that the
> name lives forever.

Fixed in v3, thanks.

> > +/// Registers a KUnit test suite.
> > +///
> > +/// # Safety
> > +///
> > +/// `test_cases` must be a NULL terminated array of test cases.
> > +///
> > +/// # Examples
> > +///
> > +/// ```ignore
> > +/// unsafe extern "C" fn test_fn(_test: *mut crate::bindings::kunit) {
> > +///     let actual = 1 + 1;
> > +///     let expected = 2;
> > +///     assert_eq!(actual, expected);
> > +/// }
> > +///
> > +/// static mut KUNIT_TEST_CASE: crate::bindings::kunit_case = crate::kunit_case(name, test_fn);
> > +/// static mut KUNIT_NULL_CASE: crate::bindings::kunit_case = crate::kunit_case_null();
> > +/// static mut KUNIT_TEST_CASES: &mut[crate::bindings::kunit_case] = unsafe {
> > +///     &mut[KUNIT_TEST_CASE, KUNIT_NULL_CASE]
> > +/// };
> > +/// crate::kunit_unsafe_test_suite!(suite_name, KUNIT_TEST_CASES);
> > +/// ```
> > +#[macro_export]
> > +macro_rules! kunit_unsafe_test_suite {
> > +    ($name:ident, $test_cases:ident) => {
> > +        const _: () = {
> > +            static KUNIT_TEST_SUITE_NAME: [i8; 256] = {
> > +                let name_u8 = core::stringify!($name).as_bytes();
> > +                let mut ret = [0; 256];
> > +
> > +                let mut i = 0;
> > +                while i < name_u8.len() {
> > +                    ret[i] = name_u8[i] as i8;
> > +                    i += 1;
> > +                }
>
> I assume the name must be zero-terminated? If so, you probably need to
> enforce that somehow, e.g. by failing if `name_u8` is longer than 255
> bytes.

Nice catch. I'm not sure how to nicely throw a compile time error in
this function, so I'm truncating it here and doing a compile error in
the macro in patch #2. This isn't ideal, but seems to work.

> > +
> > +            static mut KUNIT_TEST_SUITE: core::cell::UnsafeCell<$crate::bindings::kunit_suite> =
>
> You don't actually need UnsafeCell here since it's already `static mut`.
>

Thanks, this works.

> > +                core::cell::UnsafeCell::new($crate::bindings::kunit_suite {
> > +                    name: KUNIT_TEST_SUITE_NAME,
> > +                    // SAFETY: User is expected to pass a correct `test_cases`, hence this macro
> > +                    // named 'unsafe'.
> > +                    test_cases: unsafe { $test_cases.as_mut_ptr() },
> > +                    suite_init: None,
> > +                    suite_exit: None,
> > +                    init: None,
> > +                    exit: None,
> > +                    attr: $crate::bindings::kunit_attributes {
> > +                        speed: $crate::bindings::kunit_speed_KUNIT_SPEED_NORMAL,
> > +                    },
> > +                    status_comment: [0; 256usize],
> > +                    debugfs: core::ptr::null_mut(),
> > +                    log: core::ptr::null_mut(),
> > +                    suite_init_err: 0,
> > +                    is_init: false,
> > +                });
> > +
> > +            #[used]
> > +            #[link_section = ".kunit_test_suites"]
> > +            static mut KUNIT_TEST_SUITE_ENTRY: *const $crate::bindings::kunit_suite =
> > +                // SAFETY: `KUNIT_TEST_SUITE` is static.
> > +                unsafe { KUNIT_TEST_SUITE.get() };
>
> If you change `KUNIT_TEST_SUITE` to not be an UnsafeCell, then you'll
> want to do `core::ptr::addr_of_mut!(KUNIT_TEST_SUITE` instead.
>
> > diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
> > index b62451f64f6e..d662aa37070f 100644
> > --- a/rust/kernel/lib.rs
> > +++ b/rust/kernel/lib.rs
> > @@ -18,6 +18,7 @@
> >  #![feature(inline_const)]
> >  #![feature(lint_reasons)]
> >  #![feature(unsize)]
> > +#![feature(const_mut_refs)]
>
> Is this still needed with the above changes?
>

Yes, this seems to still be needed for the kunit_unsafe_test_suite!() macro.

Thanks,
-- David

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Re: [PATCH v2 2/3] rust: macros: add macro to easily run KUnit tests

[David Gow]

[-- Attachment #1: Type: text/plain, Size: 2148 bytes --]

On Tue, 29 Oct 2024 at 20:28, Boqun Feng <boqun.feng@gmail.com> wrote:
>
> Hi David,
>
> On Tue, Oct 29, 2024 at 05:24:18PM +0800, David Gow wrote:
> > From: José Expósito <jose.exposito89@gmail.com>
> >
> > Add a new procedural macro (`#[kunit_tests(kunit_test_suit_name)]`) to
> > run KUnit tests using a user-space like syntax.
> >
> > The macro, that should be used on modules, transforms every `#[test]`
> > in a `kunit_case!` and adds a `kunit_unsafe_test_suite!` registering
> > all of them.
> >
> > The only difference with user-space tests is that instead of using
> > `#[cfg(test)]`, `#[kunit_tests(kunit_test_suit_name)]` is used.
> >
> > Note that `#[cfg(CONFIG_KUNIT)]` is added so the test module is not
> > compiled when `CONFIG_KUNIT` is set to `n`.
> >
> > Reviewed-by: David Gow <davidgow@google.com>
> > Signed-off-by: José Expósito <jose.exposito89@gmail.com>
> > [Updated to use new const fn.]
> > Signed-off-by: David Gow <davidgow@google.com>
> > ---
> >
> > Changes since v1:
> > https://lore.kernel.org/lkml/20230720-rustbind-v1-2-c80db349e3b5@google.com/
> > - Rebased on top of rust-next
> > - Make use of the new const functions, rather than the kunit_case!()
> >   macro.
> >
> > ---
> >  MAINTAINERS          |  1 +
> >  rust/kernel/kunit.rs | 11 +++++++++++
> >  rust/macros/lib.rs   | 29 +++++++++++++++++++++++++++++
> >  3 files changed, 41 insertions(+)
> >
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index b77f4495dcf4..b65035ede675 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -12433,6 +12433,7 @@ F:    Documentation/dev-tools/kunit/
> >  F:   include/kunit/
> >  F:   lib/kunit/
> >  F:   rust/kernel/kunit.rs
> > +F:   rust/macros/kunit.rs
>
> I cannot find this file in this series, and it's not in the current
> rust-next either.
>
> (Did you do the same thing as I sometimes did: forget to `git add` a new
> file?)
>

Whoops! Thanks for catching this: I somehow managed to unstage it
while editing things. Fixed in v3:
https://lore.kernel.org/linux-kselftest/20241030045719.3085147-6-davidgow@google.com/

Cheers,
-- David

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Re: [PATCH v2 1/3] rust: kunit: add KUnit case and suite macros

[Alice Ryhl]

On Wed, Oct 30, 2024 at 5:59 AM David Gow <davidgow@google.com> wrote:
>
> On Tue, 29 Oct 2024 at 20:08, Alice Ryhl <aliceryhl@google.com> wrote:
> >
> > On Tue, Oct 29, 2024 at 10:24 AM David Gow <davidgow@google.com> wrote:
> > >
> > > From: José Expósito <jose.exposito89@gmail.com>
> > >
> > > Add a couple of Rust const functions and macros to allow to develop
> > > KUnit tests without relying on generated C code:
> > >
> > >  - The `kunit_unsafe_test_suite!` Rust macro is similar to the
> > >    `kunit_test_suite` C macro. It requires a NULL-terminated array of
> > >    test cases (see below).
> > >  - The `kunit_case` Rust function is similar to the `KUNIT_CASE` C macro.
> > >    It generates as case from the name and function.
> > >  - The `kunit_case_null` Rust function generates a NULL test case, which
> > >    is to be used as delimiter in `kunit_test_suite!`.
> > >
> > > While these functions and macros can be used on their own, a future
> > > patch will introduce another macro to create KUnit tests using a
> > > user-space like syntax.
> > >
> > > Signed-off-by: José Expósito <jose.exposito89@gmail.com>
> > > Co-developed-by: Matt Gilbride <mattgilbride@google.com>
> > > Signed-off-by: Matt Gilbride <mattgilbride@google.com>
> > > Co-developed-by: David Gow <davidgow@google.com>
> > > Signed-off-by: David Gow <davidgow@google.com>
> > > ---
> > >
> > > Changes since v1:
> > > https://lore.kernel.org/lkml/20230720-rustbind-v1-1-c80db349e3b5@google.com/
> > > - Rebase on top of rust-next
> > > - As a result, KUnit attributes are new set. These are hardcoded to the
> > >   defaults of "normal" speed and no module name.
> > > - Split the kunit_case!() macro into two const functions, kunit_case()
> > >   and kunit_case_null() (for the NULL terminator).
> > >
> > > ---
> > >  rust/kernel/kunit.rs | 108 +++++++++++++++++++++++++++++++++++++++++++
> > >  rust/kernel/lib.rs   |   1 +
> > >  2 files changed, 109 insertions(+)
> > >
> > > diff --git a/rust/kernel/kunit.rs b/rust/kernel/kunit.rs
> > > index 824da0e9738a..fc2d259db458 100644
> > > --- a/rust/kernel/kunit.rs
> > > +++ b/rust/kernel/kunit.rs
> > > @@ -161,3 +161,111 @@ macro_rules! kunit_assert_eq {
> > >          $crate::kunit_assert!($name, $file, $diff, $left == $right);
> > >      }};
> > >  }
> > > +
> > > +/// Represents an individual test case.
> > > +///
> > > +/// The test case should have the signature
> > > +/// `unsafe extern "C" fn test_case(test: *mut crate::bindings::kunit)`.
> > > +///
> > > +/// The `kunit_unsafe_test_suite!` macro expects a NULL-terminated list of test cases.
> > > +/// Use `kunit_case_null` to generate such a delimeter.
> > > +const fn kunit_case(name: &kernel::str::CStr, run_case: unsafe extern "C" fn(*mut kernel::bindings::kunit)) -> kernel::bindings::kunit_case {
> >
> > This should probably say `name: &'static CStr` to require that the
> > name lives forever.
>
> Fixed in v3, thanks.
>
> > > +/// Registers a KUnit test suite.
> > > +///
> > > +/// # Safety
> > > +///
> > > +/// `test_cases` must be a NULL terminated array of test cases.
> > > +///
> > > +/// # Examples
> > > +///
> > > +/// ```ignore
> > > +/// unsafe extern "C" fn test_fn(_test: *mut crate::bindings::kunit) {
> > > +///     let actual = 1 + 1;
> > > +///     let expected = 2;
> > > +///     assert_eq!(actual, expected);
> > > +/// }
> > > +///
> > > +/// static mut KUNIT_TEST_CASE: crate::bindings::kunit_case = crate::kunit_case(name, test_fn);
> > > +/// static mut KUNIT_NULL_CASE: crate::bindings::kunit_case = crate::kunit_case_null();
> > > +/// static mut KUNIT_TEST_CASES: &mut[crate::bindings::kunit_case] = unsafe {
> > > +///     &mut[KUNIT_TEST_CASE, KUNIT_NULL_CASE]
> > > +/// };
> > > +/// crate::kunit_unsafe_test_suite!(suite_name, KUNIT_TEST_CASES);
> > > +/// ```
> > > +#[macro_export]
> > > +macro_rules! kunit_unsafe_test_suite {
> > > +    ($name:ident, $test_cases:ident) => {
> > > +        const _: () = {
> > > +            static KUNIT_TEST_SUITE_NAME: [i8; 256] = {
> > > +                let name_u8 = core::stringify!($name).as_bytes();
> > > +                let mut ret = [0; 256];
> > > +
> > > +                let mut i = 0;
> > > +                while i < name_u8.len() {
> > > +                    ret[i] = name_u8[i] as i8;
> > > +                    i += 1;
> > > +                }
> >
> > I assume the name must be zero-terminated? If so, you probably need to
> > enforce that somehow, e.g. by failing if `name_u8` is longer than 255
> > bytes.
>
> Nice catch. I'm not sure how to nicely throw a compile time error in
> this function, so I'm truncating it here and doing a compile error in
> the macro in patch #2. This isn't ideal, but seems to work.

You should be able to just panic! if it happens.

Also, I believe it should be i < 255 instead of 256?

Alice