2023-12-18 16:11:56

by Richard Fitzgerald

Subject: [PATCH 2/2] kunit: Add example of kunit_activate_static_stub() with pointer-to-function

Adds a variant of example_static_stub_test() that shows use of a
pointer-to-function with kunit_activate_static_stub().

A const pointer to the add_one() function is declared. This
pointer-to-function is passed to kunit_activate_static_stub() and
kunit_deactivate_static_stub() instead of passing add_one directly.

Signed-off-by: Richard Fitzgerald <[email protected]>
---
lib/kunit/kunit-example-test.c | 27 +++++++++++++++++++++++++++
1 file changed, 27 insertions(+)

diff --git a/lib/kunit/kunit-example-test.c b/lib/kunit/kunit-example-test.c
index d2f7a3c62c18..9e57f341dc37 100644
--- a/lib/kunit/kunit-example-test.c
+++ b/lib/kunit/kunit-example-test.c
@@ -168,6 +168,8 @@ static int subtract_one(int i)
return i - 1;
}

+static int (* const add_one_fn_ptr)(int i) = add_one;
+
/*
* This test shows the use of static stubs.
*/
@@ -187,6 +189,30 @@ static void example_static_stub_test(struct kunit *test)
KUNIT_EXPECT_EQ(test, add_one(1), 2);
}

+/*
+ * This test shows the use of static stubs when the function being
+ * replaced is provided as a pointer-to-function instead of the
+ * actual function. This is useful for providing access to static
+ * functions in a module by exporting a pointer to that function
+ * instead of having to change the static function to a non-static
+ * exported function.
+ */
+static void example_static_stub_using_fn_ptr_test(struct kunit *test)
+{
+ /* By default, function is not stubbed. */
+ KUNIT_EXPECT_EQ(test, add_one(1), 2);
+
+ /* Replace add_one() with subtract_one(). */
+ kunit_activate_static_stub(test, add_one_fn_ptr, subtract_one);
+
+ /* add_one() is now replaced. */
+ KUNIT_EXPECT_EQ(test, add_one(1), 0);
+
+ /* Return add_one() to normal. */
+ kunit_deactivate_static_stub(test, add_one_fn_ptr);
+ KUNIT_EXPECT_EQ(test, add_one(1), 2);
+}
+
static const struct example_param {
int value;
} example_params_array[] = {
@@ -245,6 +271,7 @@ static struct kunit_case example_test_cases[] = {
KUNIT_CASE(example_mark_skipped_test),
KUNIT_CASE(example_all_expect_macros_test),
KUNIT_CASE(example_static_stub_test),
+ KUNIT_CASE(example_static_stub_using_fn_ptr_test),
KUNIT_CASE_PARAM(example_params_test, example_gen_params),
KUNIT_CASE_SLOW(example_slow_test),
{}
--
2.30.2

2023-12-19 23:17:27

by Rae Moar

Subject: Re: [PATCH 2/2] kunit: Add example of kunit_activate_static_stub() with pointer-to-function

On Mon, Dec 18, 2023 at 11:10 AM Richard Fitzgerald
<[email protected]> wrote:
>
> Adds a variant of example_static_stub_test() that shows use of a
> pointer-to-function with kunit_activate_static_stub().
>
> A const pointer to the add_one() function is declared. This
> pointer-to-function is passed to kunit_activate_static_stub() and
> kunit_deactivate_static_stub() instead of passing add_one directly.
>
> Signed-off-by: Richard Fitzgerald <[email protected]>

Hello!

This test looks good to me. However, I had issues applying this patch
so I think it needs rebasing due to the newest additions to
kselftest/kunit. But otherwise this patch looks good other than my
very small comment below.

Thanks!
-Rae

> ---
> lib/kunit/kunit-example-test.c | 27 +++++++++++++++++++++++++++
> 1 file changed, 27 insertions(+)
>
> diff --git a/lib/kunit/kunit-example-test.c b/lib/kunit/kunit-example-test.c
> index d2f7a3c62c18..9e57f341dc37 100644
> --- a/lib/kunit/kunit-example-test.c
> +++ b/lib/kunit/kunit-example-test.c
> @@ -168,6 +168,8 @@ static int subtract_one(int i)
> return i - 1;
> }
>
> +static int (* const add_one_fn_ptr)(int i) = add_one;

This is a bit of a nit but could you add a brief comment above this
pointer definition? This would then match the commenting on the other
functions in kunit-example-test and provide more context for those
looking at the example tests.

> +
> /*
> * This test shows the use of static stubs.
> */
> @@ -187,6 +189,30 @@ static void example_static_stub_test(struct kunit *test)
> KUNIT_EXPECT_EQ(test, add_one(1), 2);
> }
>
> +/*
> + * This test shows the use of static stubs when the function being
> + * replaced is provided as a pointer-to-function instead of the
> + * actual function. This is useful for providing access to static
> + * functions in a module by exporting a pointer to that function
> + * instead of having to change the static function to a non-static
> + * exported function.
> + */
> +static void example_static_stub_using_fn_ptr_test(struct kunit *test)
> +{
> + /* By default, function is not stubbed. */
> + KUNIT_EXPECT_EQ(test, add_one(1), 2);
> +
> + /* Replace add_one() with subtract_one(). */
> + kunit_activate_static_stub(test, add_one_fn_ptr, subtract_one);
> +
> + /* add_one() is now replaced. */
> + KUNIT_EXPECT_EQ(test, add_one(1), 0);
> +
> + /* Return add_one() to normal. */
> + kunit_deactivate_static_stub(test, add_one_fn_ptr);
> + KUNIT_EXPECT_EQ(test, add_one(1), 2);
> +}
> +
> static const struct example_param {
> int value;
> } example_params_array[] = {
> @@ -245,6 +271,7 @@ static struct kunit_case example_test_cases[] = {
> KUNIT_CASE(example_mark_skipped_test),
> KUNIT_CASE(example_all_expect_macros_test),
> KUNIT_CASE(example_static_stub_test),
> + KUNIT_CASE(example_static_stub_using_fn_ptr_test),
> KUNIT_CASE_PARAM(example_params_test, example_gen_params),
> KUNIT_CASE_SLOW(example_slow_test),
> {}
> --
> 2.30.2
>