Documentation: rust: testing: add Kconfig guidance

Now that the Rust KUnit tests are protected with Kconfig, update the
documentation to mention it.

Signed-off-by: Yury Norov <ynorov@nvidia.com>
Reviewed-by: David Gow <david@davidgow.net>
Acked-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260417031531.315281-4-ynorov@nvidia.com
[ Fixed the paragraph by moving the new sentence above. Added gate
  in the other example as well. Applied proper formatting. Reworded
  slightly. - Miguel ]
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

1 files changed, 5 insertions, 0 deletions

diff --git a/Documentation/rust/testing.rst b/Documentation/rust/testing.rst
index f43cb77bcc69..e3943aceceb9 100644
--- a/Documentation/rust/testing.rst
+++ b/Documentation/rust/testing.rst
@@ -140,11 +140,15 @@ 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.
 
+Each test suite should be guarded by a Kconfig option in
+``rust/kernel/Kconfig.test``.
+
 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
 
+	#[cfg(CONFIG_RUST_MYMOD_KUNIT_TEST)]
 	#[kunit_tests(rust_kernel_mymod)]
 	mod tests {
 	    use super::*;
@@ -173,6 +177,7 @@ the unit type ``()``) or ``Result`` (i.e. any ``Result<T, E>``). For instance:
 
 .. code-block:: rust
 
+	#[cfg(CONFIG_RUST_MYMOD_KUNIT_TEST)]
 	#[kunit_tests(rust_kernel_mymod)]
 	mod tests {
 	    use super::*;