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

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

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

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