Re: [PATCH v2 2/2] lib/math/rational: Add Kunit test cases

From: Daniel Latypov
Date: Tue May 25 2021 - 13:34:47 EST


On Tue, May 25, 2021 at 7:43 AM Trent Piepho <tpiepho@xxxxxxxxx> wrote:
>
> Adds a number of test cases that cover a range of possible code paths.
>
> Signed-off-by: Trent Piepho <tpiepho@xxxxxxxxx>

Reviewed-by: Daniel Latypov <dlatypov@xxxxxxxxxx>

Looks really good to me, just two nits.

Tangent:
I didn't check to see that this covers all the interesting cases, but
it seems like it does.
If you want, you can try generating a code coverage report to double check.
Instructions for doing so can be found in
https://lore.kernel.org/linux-kselftest/20210414222256.1280532-1-dlatypov@xxxxxxxxxx/
I would have done that and included the #s in this email, but my
workplace decided to subtly break my workstation in some way and I
haven't gotten around to root causing...

> ---
> lib/Kconfig.debug | 12 +++++++++
> lib/math/Makefile | 1 +
> lib/math/rational-test.c | 56 ++++++++++++++++++++++++++++++++++++++++

Ah, sorry, I forgot to mention this in the previous email.
If you look at kunit/style.rst docs, you'll see the documentation now
states a preference for the name of this file to be one of
{rational_test.c, rational_kunit.c}

Unfortunately, we have a number of tests throughout the tree that
don't reflect this, including lib/kunit/kunit-example-test.c :(

> 3 files changed, 69 insertions(+)
> create mode 100644 lib/math/rational-test.c
>
> diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> index 678c13967580..6c0e66a7d416 100644
> --- a/lib/Kconfig.debug
> +++ b/lib/Kconfig.debug
> @@ -2429,6 +2429,18 @@ config BITS_TEST
>
> If unsure, say N.
>
> +config RATIONAL_KUNIT_TEST
> + tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS
> + depends on KUNIT
> + select RATIONAL
> + default KUNIT_ALL_TESTS
> + help
> + This builds the rational math unit test.
> + For more information on KUnit and unit tests in general please refer
> + to the KUnit documentation in Documentation/dev-tools/kunit/.
> +
> + If unsure, say N.
> +
> config TEST_UDELAY
> tristate "udelay test driver"
> help
> diff --git a/lib/math/Makefile b/lib/math/Makefile
> index 7456edb864fc..bfac26ddfc22 100644
> --- a/lib/math/Makefile
> +++ b/lib/math/Makefile
> @@ -6,3 +6,4 @@ obj-$(CONFIG_PRIME_NUMBERS) += prime_numbers.o
> obj-$(CONFIG_RATIONAL) += rational.o
>
> obj-$(CONFIG_TEST_DIV64) += test_div64.o
> +obj-$(CONFIG_RATIONAL_KUNIT_TEST) += rational-test.o
> diff --git a/lib/math/rational-test.c b/lib/math/rational-test.c
> new file mode 100644
> index 000000000000..f64166dbe9ea
> --- /dev/null
> +++ b/lib/math/rational-test.c
> @@ -0,0 +1,56 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +#include <kunit/test.h>
> +
> +#include <linux/rational.h>
> +
> +struct rational_test_param {
> + unsigned long num, den;
> + unsigned long max_num, max_den;
> + unsigned long exp_num, exp_den;
> +
> + const char *name;
> +};
> +
> +static const struct rational_test_param test_parameters[] = {
> + { 1230, 10, 100, 20, 100, 1, "Exceeds bounds, semi-convergent term > ½ last term" },
> + { 34567,100, 120, 20, 120, 1, "Exceeds bounds, semi-convergent term < ½ last term" },

very minor nit: there's an extraneous space character after the "100,"

> + { 1, 30, 100, 10, 0, 1, "Closest to zero" },
> + { 1, 19, 100, 10, 1, 10, "Closest to smallest non-zero" },
> + { 27,32, 16, 16, 11, 13, "Use convergent" },
> + { 1155, 7735, 255, 255, 33, 221, "Exact answer" },
> + { 87, 32, 70, 32, 68, 25, "Semiconvergent, numerator limit" },
> + { 14533, 4626, 15000, 2400, 7433, 2366, "Semiconvergent, demominator limit" },
> +};
> +
> +static void get_desc(const struct rational_test_param *param, char *desc)
> +{
> + strscpy(desc, param->name, KUNIT_PARAM_DESC_SIZE);
> +}
> +
> +/* Creates function rational_gen_params */
> +KUNIT_ARRAY_PARAM(rational, test_parameters, get_desc);
> +
> +static void rational_test(struct kunit *test)
> +{
> + const struct rational_test_param *param = (const struct rational_test_param *)test->param_value;
> + unsigned long n = 0, d = 0;
> +
> + rational_best_approximation(param->num, param->den, param->max_num, param->max_den, &n, &d);
> + KUNIT_EXPECT_EQ(test, n, param->exp_num);
> + KUNIT_EXPECT_EQ(test, d, param->exp_den);
> +}
> +
> +static struct kunit_case rational_test_cases[] = {
> + KUNIT_CASE_PARAM(rational_test, rational_gen_params),
> + {}
> +};
> +
> +static struct kunit_suite rational_test_suite = {
> + .name = "rational",
> + .test_cases = rational_test_cases,
> +};
> +
> +kunit_test_suites(&rational_test_suite);
> +
> +MODULE_LICENSE("GPL v2");
> --
> 2.26.2
>